+1 on everything 03LimitedEditionRaptor said. I cheaped out on a $10 front sprocket. After maybe 10 hours of ride time it was missing 2 teeth. I do have the same chain that 03 suggested and have had it for 2 years now. It stretched after a couple of hours of ride time, but no more stretching after one adjustment. Great chain.I would just pice it together.
For a chain get a gold RK GB520EXW chain. It has a tensel strength of 8500, and has better sealing rings than the standard x ring chain. It comes with a clip style master link. I run this chain both on my banshee and raptor in my signature.
For the front sprocket get a good one. Dont cheap out with a 5-10 dollar front one. It takes the most abuse and a good one should be run.
SuperSprox or a Renthal.
The rear sprocket isnt as critical because it has more teeth and takes way less abuse. Just make sure you run a steel one. Aluminum will not last verry long and they are quite a bit more expensive.