If it brings you joy, then I can't take that away. The whole Che thing has been done to death though. If I hadn't have seen the image a million times in corporate malls and stores, than I would probably like it a lot more... but the man spent his whole life fighting against capitalism and corporate buildup. The reality is that his face on t-shirts has become nothing more than trendy... and by buying the shirts, you are technically going against what the man stood for. It really makes me sad that statements don't mean anything these days...
However, you technically didn't buy a shirt. You drew a picture. A pretty good one at that (assuming you didn't trace, stencil, etc.). And for that, I have no problem with. I just wish the "revolutionary" types would do something original for once.