Agreed with Joshua, a single ssd will have way more performance than all 15 of those for random io for sure, and probably be very close on sequential. That said, a raid controller able to handle all 15 drives (or multiple that handle a subset of the drives) is likely to be more expensive than a single good ssd, or a couple / few pretty good ssd's.
It's really amazing how much solid state drives transferred the database bottleneck away from disk.