Yeah I didn't really take into account the GameCube versions might be priced pretty highly. I bought mine as they were released, so I guess they've become something of collector's items. The only reason I like the CG versions is because I have the full series on one system and I still play them on the Wii to this day. You can't beat playing through all six games from 0-4 in sequence.
Get them on whatever system you can find them for at the price you're willing to play.
Besides, the remake is quite different in many ways than the original, you'll get different experiences with both games.