That's very common with the ebay resellers. It's annoying, but it's true. Much of the money those ebay resellers make in profit comes from using their own closing company. In some cases, the closing company and the ebay seller are one in the same (or closely affiliated).
The good news is, in many cases, closings go very well. Factor that in to what you are bidding - since you can't use your own company and the closing costs are typically on the higher end, when you bid, make sure you pay attention to what it costs total (Bid + closing company costs).
I'm in the process of closing on a timeshare in HHI and it has gone very well. For what I paid for the timeshare itself, the slightly increased closing costs more than made up for it. Although there is not really buyer protection on ebay, you can still leave bad feedback and most of those sellers really seem to care about it. In most cases, I think you'll be all right. Do some searching here on TUG, because I don't think every reseller on ebay is rated the same.