If you haven't tried a dealer parts department, I would suggest that first (taking some doughnuts may encourage them to spend time tracking down a part for you). They really have the most complete parts databases, especially for body parts like this. If you can get a part number from them, you can possibly find a cheaper source for it online (You want someplace that will sell you the part for a price somewhere between wholesale and retail, the closer to wholesale the better). Some forum posts I saw indicate availability, for a price, though it wasn't clear to me if it was the whole assembly or the individual holders. Given the complaints on pricing, I'd guess possibly the latter.
Most of the assemblies I see on eBay are without the bulb holders. I suspect this is a common fault and a highly desired part.
You can always try a boneyard (junkyard). If you're in the US, Pick-n-Pull is my favorite. Given the eBay situation though, I suspect you may find the inventory picked over. In that case, keep checking until a fresh one comes in and then head down and get to it before anybody else does.