Dude, this cost is just unrealistic.
You don't have to pay an artist to redo all the sprites, that's a waste of time and money.
You can start from the sprites you have and pay some talented guy to work just in the edges of the sprites, where it's uglier (no offense), and insert a couple of new ones. It wouldn't be 1/10 as expensive as you have put in here.
Another solution is just to put an output video processing in the sprites, the same ways Zsnes and Snes9x do to beautify the old sprites from snes.
ZSnes is open source, so you can just rip the algorithm from there.
After playing a couple of matches in medium difficulty, i realized that the computer makes a lot less mistakes than in real life, even real life Federer isn't as good as those guys. And the same goes to us, human players. Unforced errors and mainly forced errors should be more common.
That's my opinion.
And about the other post, errr, you know, that was my little brother