As for the slightly pricey fighters: Last Blade 1, 2 and Art of Fighting 3, then you are set in my opinion. Games like Samurai Showdown 1, 3, Fatal Fury 1, 2 and a few others are pretty cheap in price. My priority was to get all of the FF (Real Bout and Mark of the Wolves included), AOF, LB, SS and KOF games... which I did except for later made Playmore titles and for some reason I still never got a copy of KOF 94, but will.
For some other low price fun you can always get NAM-1975 (A must and the first NG game), Magician Lord, Mutation Nation, and either 3 Count Bout or a King of The Monsters game.