DLP TV picture only comes on after the TV has been sitting a while.?

If the set have a picture only after being turned on for quite a while, then it's a mix of a weak lamp and weak ballast. The lamp is user replaceable, the ballast is not.

If you have to wait to turn the set on after turning it off, it likely needs a good cleaning and have the fans checked as it may have an overheating issue.

There is no definite answer - this one comes down to hands-on diagnosis. If this is a smaller DLP set, like a 42", you can't afford to invest much into it. Last 42" DLP set I had was donated, by me, to the Salvation Army. When I sold it's 56" replacement, I pulled an entire $120 for it in excellent working condition with a recent lamp. You just can't invest much time into a DLP anymore, as good as they were.

Thanks. I went and bought a new LED. So cheap, so good, wow. I just hadn't realized how much things had changed in the last few years. Thanks & enjoy!