Fix phone or replace with refurb?

[cheesehead]

My phone recently went kaput, and I'm trying to figure out what to do. I'm not sure if it's the screen or the logic board, and while I could probably replace the parts, I'm not familiar enough with the hardware to do any diagnostics.

Is there a good place for getting cell phones fixed? Or am I better off just buying an AT&T-compatible refurb?