You may want to try BBR for the electric start. I know they've done some things with the XR200 engine in the past, and they can put electric start on the 400's, so you might be in luck with them. www.bbrmotorsports.com
Adding electric start to the XR200 is possible. They have an electric start 200 in Japan.
You'd have to get a contact in Japan and order the following items: Cases (inner left and right), starter gears, starter motor, stator, wiring harness. This should put you back about $1,500 - $2,000 US, without the shipping. You'll have to completely disassemble the engine to install these components.
Needless to say, if you want an electric start bike, you might want to just purchase one. The Yamaha Serow (ttr225) is comparable to the XR200 in handling and power and has electric start to begin with.
For legalizing the XR, go with the Baja Designs kit. It's quick and easy and works very well. You'll have to send your stator in for rewinding though, as the stock one doesn't have enough juice to run lights and turn signals.
The Suzuki DR200SE is a street legal dualsport with elect start. Nice little bike, but not a racing tool. The one I rode did 55 mph with a passenger without laboring too hard. A taller option would be the XR250L-also elect start. These are the cheap options-sell the XR200 and put the money towards one of these.