You can take a couple of routes for the wheels and spacers.
for our 50 I took the wheels from our Raptor 80 and mounted them on the 50 with 2" lug type spacers. I got the spacers on ebay for front and back for about $100. this worked out ok. I decided to put the raptor 80 wheels on the 50 to give slightly more ground clearance but you can just mount the 50 wheels back on with the lug type spacers.
for the Raptor 80 I bought the 2" aluminum wheel spacers for front and back and ITP offset rims and tires. the raptor 80 handles awesome and looks good. The spacers cost me $150 for all four wheels and the tires and rims where $400. The spacers are normally $110 a pair but I have seen them on ebay for $55.00 a pair. the tire package is also on ebay. try doing a search on Raptor 80. also if you do a search on yamaha badger, yfm80, yamaha champ, yfm100 on ebay it will yield many parts and some accessories that will fit the raptors. there are also sites out there that sell cooler racks, grab bars, front bumpers, exhausts, etc ... for the raptor 50/80 all depends on the money you want to spend.
another site you can check out is raptor80racing.com for parts. most if not all of the 80 parts (exhaust, wheels, etc ..) will fit the 50.
I purchased my spacers from
http://www.weirdharoldscoolparts.com/ the price was good however it took a couple of months and a number of phone calls to get them to send the spacers after I ordered them so ......