Hello Piece0fYou and welcome to the forums!
There isn't a lot I can add here that hasn't already been discussed, but if I were you I would stick to collecting whichever version of the artwork you enjoy most. If you like the old art but are collecting new art because it's easier to obtain then you're never going to enjoy your collection as much as you otherwise might have done. But old art is a lot harder to get now.
Have you thought about whether you really must have literally everything? Some of the expansions are a bit hit and miss even amongst the more seasoned veterans. Perhaps you'd be better building up a small collection based on what you like, and enjoy playing, and then move on from there once you're ready if indeed you still want to. Tunnels for example, is highly sought after, but it isn't that fun to play and it doesn't really add that much to the game. Have a look at JCloisterZone (
http://jcloisterzone.com/en/) if you want to "try before you buy" for some of the more difficult to find expansions...
Hope this helps!
Dan