agreed. games read a lot of random data. performance won't be nearly as 'good' as op expects.
the difference of $50 matters that much for op, i think that not spending anything would be the more prudent choice.
that said, if it were me i'd raid-0 two of them and keep the third as a single drop-in replacement for when that array dies; containing a full backup of the array's contents kept up-to-date with every major patch the games on it gets.