Been Around the Block
I'm going to tell you right now that the majority of people when asking for custom 3D models, bitz, swords etc, in the majority of cases, are unwilling and surprised by the pricing of custom work.
This can be especially shocking to some because the industry at large has massive collection dumps of STL printable armies for around 10$ to 50$ for a crap ton of models.
So when you factor that in a negotiation for doing a model for someone the often result is people automatically think you're over charging, especially in the miniatures world.
The same people that are surprised by the cost, often get angry, look for alternatives that are cheaper, turn to getting free STL files.
How much on average does it cost to hire an artist / 3D modeller etc. That all depends on the job, skill, and time required for the project, the designers available asset library, and how much they value their time.
So on average a 3D modeller doing a custom job for you can cost anywhere from 15$ to 150$ hour, to over 7000$ USD for character concepts and illustrations, especially on the commercial end, and that does not include royalties, copyrights etc.
On the none commercial end I've seen an average of 200 to 500$ per character give or take. ( I didn't set these prices I checked in with some university proffs on pricing models, and spoke to other industry artists about current rates, this is accurate)
So why why would you pay out the rear end for an artist, figuratively speaking ? I'll try to explain a few reasons that will be relevant to the above post.
One of the reasons would be that you're interested in commercial use, you're designing a table top game etc, making a product etc. The reasons here you would not want to go with license free STL files is the very same reason you wouldn't want to be in a zombie apocalypse running for the hills.
Because everyone else has done it, or is already doing it. Meaning you could land yourself in hot water, being eaten alive by zombies, or getting into copyright law on the wrong end of the stick. You can't reasonably sure that STL file is original work, and for that same reason you can be sued.
There are hundreds if not thousands of copy cats in the industry buying high, and selling cheap of original sculpts on the global market that don't belong to them. That could easily get you into trouble legally.
So yes you can get open source free sculpts, but it's not conducive to having a good project. The sculpts are often poor quality and are not uniform. etc. Many are really good as well so sometimes you can luck out. Just keep in mind that if you're buying online for commercial uses. Know your source.
Reason two well, the sculpts are just not what you're looking for and you need something different, or completely unique, that is one of the reasons you would hire an artist.
That being said what about for personal use? Well the majority of you I will tell you honestly are unwilling to pay the average price an artists will charge you on the low end. I know this personally because I've had to hire artists in the past, and it's always a pain to get a fair deal.
The main reason you're not willing to fork over the cash is that majority of people are just looking for bitz, that are a product from a company already finished and in production, or only willing to pay for the finished model and expect it costs around 20$USD for a figure.
Well that's a gross underestimate of costs, why you might ask? Mostly the reason that hiring someone for custom work is more expensive is as follows. The over inflation of the art industry graduates believing they're an essential service like a plumber, the ghost of "material costs" still lingers in the industry, and the high price of schooling, software cost, equipment cost, and hours learning.
All of the above factors into staggering prices for hiring someone and I say it's mostly unjust. We're often today being charged for material costs that simply don't exist, and paying for tools the artist is using and their education. Which is something I personally think is unfair, but that's just me.
What's more interesting is that the industry is turning into a global market, people are able to and willing to sculpt for extremely low prices, don't have to pay for college expenses, don't have to pay for materiel costs, and don't have to pay for software or hardware.
This is essentially similar to the 50cent haircut, and the 15cent haircut. Supply and demand.
So should you hire a sculptor .. no I don't think you should, not unless you want something truly unique, or unless hiring someone else saves you time and money, you will never truly be happy with the results unless you draw a proper concept sketch. No one is going to get it exactly the way you want, and everyone is going to have a different idea of what "cool" looks like.
Why would you hire me. Well I'll be upfront about the industry at larges costs, I charge a middling price for my time not the highest or lowest, and am willing and able to re sculpt something or work on revisions, and I will do my best not to BS you or throw in hidden fee's.
And I know how to sculpt miniatures, where staggering amount of sculptors don't are trained for specifically video game design. I also have an extensive library of assets that I can combine to speed up sculpting time. I also have an ironclad contract and copy right lawyer's that ensures that all the tricky copy right law is above board for commercial uses. You go with me and you minimize risk for a random artist coming after you legally for copyright abuse, such as a number of high profile cases currently going on because of animated avatars on twitch, as one example. There are surprising pitfalls in the legal area getting a table top game to launch and you want to ensure that you're legally protected for your products. And getting a commission project from someone that understands this fact can save you in the tens of thousands later on. One example would be a sculptor copying someone's work and you producing that.
In conclusion if you really want just cool miniatures to paint go with FREE to low cost STL dumps online, or learn the skill yourself it's no less complex then painting, and can be around the same price as collecting an army.
If you're unwilling to do either and have a lot of extra cash on hand, Somewhere there is a poor starving artist willing to make your zombie unicorn, four armed, centaur, cyborg, with a bionic leg.