Actually, I believe the maximum amount is capped at 250k, which is obtained by killing 10 in the correct order. Levels with more than 10 will only give the 250k big crystal.
Either way, if it did keep up the point trend for more than 10 enemies, then level 96 (with 6 apricots) would have 18 enemies; 6 of the originals, plus the 12 that spawn from them. The amount for the big crystal would then be 810k

Damn...