how hard is it to find games for the older consoles these days?
If you wanted just the game, I'd imagine it wouldn't be too difficult.
Locally, there are a few stores that sell old games. 2 of them sell games mostly loose for $1.99-$19.99 for the most part except for some of the harder to find games. Another store sells games in their original packages for $49-$300.
Looking online real quick, prices seem to be around there. You can get the first Final Fantasy game for $10 used for $249 new in box.
I don't buy too many old games though. The last I bought were to replace a few missing Sega Genesis games I had a couple years ago... I picked up 10 or so games for about $30 off ebay or Amazon, I don't remember which.