Guess this is going here, since I apparently don't have the permissions to post in the classifieds.

Would anybody have an HVAC mode door they'd be willing to sell, or be able to direct me somewhere online I could buy one that's actually in stock?

Part No. 15-50554 / 52470781
for
2003 Chevy Blazer LS

 

Find one at a junkyard, pulling the whole unit is easier than fixing the doors and you know what your getting into before you break anything on your ride. There is a good video on youtube on rebuilding the hvac unit shows you how to replace all the plastic levers and stuff thats in there so it is doable. Good luck.