OK, so 65 pages later I make an ID to post.
It seems like a major complaint here is being unable to play or unable to play with your friends when you GM. I suppose there are two types of GMs then.
GMs that just want to run the game.
and
GMs that want to run the game and play the game.
So the ideas is to reward both types of GMs fairly. I find it rather difficult to reward GMs that just want to run the game. Perhaps special adventures as rewards. Adventures that are only given out when GMs meet certain milestones. (such as running a certain number of games or attending a certain number of events) What better way to reward someone who enjoys running the game than giving them more game to run!
Physical rewards are also ideal for a GM that just wants to run the game.
Tokens, Glass or plastic counters, and GM-screens are all rather "cheap" to produce items that can really help a GM out. On the higher end of physical rewards you may want to present Minis, artwork, or play-mats as rewards. (What it takes to earn these can be balanced out as needed)
For GMs that want to play with their friends as well as run the game. The options above would be available to them (and no less desirable). An addition to the above rewards GMs who want to play may run games to earn pregenerated character sheets. This although sacrificing some of the freedom their friends have with selection of gear and items, allows the GM to play with (and grow) a competent character that is balanced for the level its generated for. So as you GM more and more and your players rise in level, you'll always have the chance to pull out bob the fighter and head on over to an event with your pals to wreck some house.
I hope I helped!