I'm on my third bulb/housing for my Optoma. The first two were OEM; the next one aftermarket.
The aftermarket has >2000 hours on it and cost $246 (which was WAY less than OEM at the time) and looks great.
I always have a spare bulb/housing handy, and the one on the shelf right now is aftermarket as well and cost ~$120. As I did with my other bulbs, I have already used it for ~1 hour in the projector as soon as I bought it. My theory is that this way I minimize the risk of "infant mortality" (and could return it right away if it fails) and get to make sure it looks ok (which it did.)
I've looked online and can now get aftermarket bulb/housings for $60. I've also found a seller claiming an OEM bulb/housing for the same price. I'll likely order one or two more bulbs at that price next year to keep the PJ going well into the future.
I'd been considering / looking at 4k models (mine's a 720p DarkChip 4 DLP), but the picture is so darn good (amazing blacks, terrific colours, all the brightness I'd ever want, etc.) on the one I have that I think I'll wait for quite a while before I do anything. And at $60 a bulb that could be a long time!
Jeff