All good, depends on three things -
1) How many channels you want.
2) What RAID levels you want (0,1,5,0+1).
3) Biggie, how much your willing to part with money wise.
$71 gets you a dual channel (2 drives) RAID 0, 1 or JBOD - Adaptec 1210SA
After that it jumps way up ($200+)