you can kill 2 birds with 1 stone, if you want...

you can get a pair of new Reynolds Race wheels on e-bay for about $199, and you also get a new Shimano 105 rear cog with 12-27 gearing on e-bay for about $60. so, you figure about $300 with shipping...

if you do decide to go with the cranks, look into it, i personally wouldn't go with FSA cranks...