I've got 6 of those horrible DLP's at my office. They claim 2000-4000 hours, but half life is when you change them due to loss of brightness and clarity. I'd say take what they claim is the lamp life and expect to change it at about 25-50% of that. My old projector was a DLP, it claimed 4000 hours per lamp, but the reality was it needed to be changed at 1500 hours. Sure it continued to display a picture, but the clarity and brightness had degraded enough that I had to replace it. Now I just use the new projector for movies or to watch an occasional game.
I'm just suggesting based on my expirence with them that it's better to spend the extra $1k now then to deal with replacing lamps. The other problem I've run into, after a few years the bulb is no longer produced, at least not in the quantity they were when the set first came out. So they become harder to find and the cost goes up. I had to scrap one projector after 5 years because I couldn't find a bulb for under $650 and we deemed it better to buy a new projector than a nw bulb.
One more thing, I had the color wheel go out in my old DLP projector after 2 years, I had paid $1k for the projector new. But they wanted $800 to fix it. Yes, I sold it for parts on eBay.