I didn't really chime in on this, but lamp vs. bulb replacement is a question that comes up over the years and there are several reasons to buy a lamp, and one reason not to.
Replacing the bulb inside a lamp assembly is easy. The bulb really is designed to fit a very specific way and the rest is designed to handle projecting the light from the bulb through the lamp properly. It's not overly dangerous to swap out, and general caution should be taken, just as you would do with a car light bulb. Typically, there are solid instructions with a bare bulb, on how to replace it in the projector. If not, there is always YouTube.
So, yeah, not a big deal to replace the just the bulb yourself inside the existing lamp chassis.
If it is easy, and it saves you $100 or more, why not just do this all the time instead of dropping $200 or far more on a manufacturer branded original lamp?
Well, it could cost you your entire projector.
The lamp itself has parts to it and the manufacturer bulb also, protects against heat and UV radiation. This is perhaps the top issue I've heard of in the last 15+ years of digital projection. People put in a replacement bulb and it runs hot. It burns up the plastic internals of the projector, most often the lens, and the entire projector is ruined. I have also heard of it blowing out power supplies because it draws more voltage than the projector is designed for. Other issues? I've heard of aftermarket lamps that blow out in 500 hours when the original lamp lasted 2,500 hours. So, any cost savings are removed. I've heard of lamps which are significantly dimmer than the manufacturer lamps, so they aren't restoring the projector to out of the box quality.
These issues aren't something that always happen, but it does happen and if you gamble on a aftermarket bare bulb, or even after market complete lamp, you may run into any of these issues. The odds seems to be better that you get a decent after market product these days, but it's not 100% at this point. Not even close.
If your projector is cheap (sub $1,000) and you use it often, say 2,000+ hours a year, and replacement lamps are pricey. Then doing a bit of homework on bare bulb replacements is a good idea. You are far more likely to get a acceptable replacement and get another 1,500+ hours of usable life from that lamp then it is to hurt your projector or fail very early.
Better! Know your lamp replacement costs before you buy. Epson leads the market with their cheap lamps, but the market is changing and the days of cheap projectors and $200+ replacement lamps are pretty much gone. Epson changed the game and has solid entry level projectors with Epson original replacement lamps as low as 50 bucks. In a recent article from Projector Central, here were the published lamp prices for a manufacturer original replacement lamp:
Epson HC 1060 $49
Optoma HD143X $89
Optoma HD27e $89
ViewSonic PJD7720HD $99
ViewSonic PJD7828HDL $99
BenQ HT1070A $149
ViewSonic Pro 7827HD $149
Optoma HD29Darbee $179
So, there is an obvious shift from the traditional $250+ lamps of just five years ago to more realistic lamp pricing. This move, I believe, is about fighting solid state lamps such as LED and laser models, which will be taking over at some point as a default. No doubt that the less expensive Epson models are very consumer friendly on lamp pricing while delivering a solid entry level home theater image.
Meanwhile, entry level products from most manufacturers are staying under $100 for replacement lamps, which I think should be a target price. If any manufacturer had lamps at $100 or less, I would say that at no point should anyone buy anything else. I also believe it hurts manufacturers (BenQ!!!) when they have significantly higher prices and don't drop them to match the competition.
