Stock is good. There are several aftermarket companies that make one or both levers. Assuming you have the stock perch (the part that attaches to the handlebars), you have lots of options.
According to my book, all years will use the same clutch lever. Brake levers are dependant on year. I agree with Xracer about using the lever from another model. Unfortunately, due to fitment charts, you have lots of choices that won't be listed online since the manufacturer lists the lever for something like a YZ but not the TW, even though it might fit both.
For cost and quality, I use Moose Racing quite a bit. I think you'll find that all brands will do a good job.
I'm a bit biased when it comes to retailers, so I'll (*cough* Perfmoto.com *cough*) stay out of it.
Congrats on the new bike!
Snoop