my buddy gave me a set of itp ss rims off his polaris atp 500 thought they would fit but didnthole pattern was fine but center of rim just a little to small

 

Doesnt sound like anything that would slow down a machine shop with a decent lathe.

Ive had custom work done like that here at a local place....most of the time its very reasonable. I had them make me a spindle for a chinese ATV....charged me $40 - not bad considering the work involved.

 

I would also try a good machine shop. They might charge $10 a rim and you'd end up with 4 nice rims on your Sporty.