You can get handlebar risers from a number of places (Wunderlich, Touratech, etc). These are basically replacements for your current handlebar clamps. However read on first before buying...
Unless you really binned your bike, I think you'll find that you haven't bent anything. The handlebar clamps are bolted to the headstock through rubber mounts, and have simply shifted slightly. Undo the nuts holding the clamps to the headstock, push the bars back into the right position, then do up the nuts again.
I found it disturbingly easy to bend the original steel bars on my XT600E. Since then I've fitted a set of Renthal Paris-Dakar bars which so far have been indestructable. My experience is that the mounts just shift, rather than the bars bending. Note that any replacement bars are likely to have slightly different dimensions (height, rake, etc.), so I would recomend getting some new bars first, then deciding if you need to get the risers.
Also, go for some aluminium brush guards to protect your levers and fingers. I've fitted some Acerbis Rally-Pro guards, which I've tested extensively by lobbing the bike at the scenery many times, and I've yet to even scratch a lever.
Hope this helps.
Iain.
'99 XT600E
'01 XRV750
Morocco Trip
http://iain.woolley.net/Trips/Maroc2001