Just my Marines alone would be reaching towards $5k in current (Australian) prices. With my other armies, games, terrain, and supplies I'd have absolutely no idea but it would be quite a bit more. Also I didn't pay that much at the time - I bought a large number of the combat squad + razorback sets when Apoc came out, gifts, and that sort of thing.
That said it's been bought up over 20 years so on a yearly cost it can seem quite cheap, expecially when I think that I just spent almost $2.5k on a new computer. The main thing for me is time now - I need more of that to put the stuff together and paint it... but if I had the time I wouldn't be making the money to buy the stuff I need the time for!