There is absolutely nothing wrong with Epic. In fact, it is an incredible game.
Epic rules are currently available for download for free from the main
GW site. Epic minis are officially only available from
GW direct. However, as noted, eBay is a great source. These can go from the crazy expensive (anything Tyranid) to the incredibly cheap (plastic Orks, Marines, etc which have been around for years, came in the original game sets and so pretty much everyone has hundred of already).
The comment about
FW was bang on. This is possibly the only time where
FW are actually cheaper than
GW minis. Take a look and compare for yourself.
I think that the £100 mark is a little higher than I would guess for a standard 2700/3000 point army. Start by just picking up an infantry company and perhaps a Leman Russ Co. Play a few games with these to get the hang of it. Then you can expand to around 2000 points, but avoid space vessels, aircraft and war engines at this stage. This should make your games flow easier and allows you to learn the standard rules.
Once you have done this, you will probably be a fanatic about the game, and be looking at 3000 point armies for pretty much every race you can!