Now that GameMaker Studio is released (or very shortly), GM:HTML5 ($99) will no long be for sale. At $99 it was only $20 more than C2 which wasn't bad. Now, in order to make HTML5 games with GM you have to buy GameMaker Studio ($99) then the HTML5 exporter ($99) for a total of $198! You'd really have to love GM to pay an extra $119 just to use it for HTML5 instead of C2. Furthermore, they want an extra $199 for every exporter! Compared to the free CocooonJS, AppMobi, and impending Awesomium exporters you get with C2... GM is a complete rip-off. Officially the best $32 I've spent in a long time! (I'd still be happy if I had paid $79).
EDIT: As Wink pointed out the HTML5 export is $99. A while ago they said each export would cost an additional $199. Looks like they changed their minds about HTML5. Sorry for the misinformation, I've corrected the above numbers.