This is the site for everything to do with space ship combat games.
http://www.star-ranger.com/Home.htm
To summarise, there is a huge variety of rules and models available. Most models are cheaper than
BFG.
The best rules give you preset ship designs and a system to let you develop your own designs to suit any models you might want to pick up.
Starmada is a good system
IMO, with medium complexity, some good options and reasonable fleet size.
I used to like Starfire but it has grown too big and complex now.