If you limit is $200, then I would do what ironchef2009 suggested, although I feel the power gains will be pretty minimal. The stock muffler is pretty restrictive, look how small the opening is and it is baffled, so a slip on would provide alot more exhaust flow, since it is just a straight though pipe. I have never tried the Lexx brand slip on's, but I have heard good things about them. I figure all slip on's are pretty much the same, not really a whole lot you can do using the stock headpipe, might as well get the cheapest one you can.
As far as a cam, I believe site sponsor EHS did a before and after dyno test on a "big 3" 700XX and Hot Cams stage 3 cam. (Dyno sheets should be on this site somewhere.) I want to say the quad picked up something like 3 or 4 horsepower after the cam install. My one 700 has the big 3 and I installed a stage 3 cam and it was a noticeable difference. What are your future plans? If you never really plan on getting into the motor, then a Stage 3 cam would be a good investment. Now if you plan on gettting the head ported eventually along with other work, then I would hold off and get a Web cam and spring kit later down the road.
For a budget motor that you never really plan on doing anything else with, I would go with a Lexx slip-on, EFI controller, remove airbox lid, and a Stage 3 cam. Will be a very noticeable difference compared to stock.
Doug