Hi, I don't think buying / selling real estate at eBay works in the same process as any tangible product listing. There are a lot of things you need to check on and considering the enormous amount of money to release as payment, it will never be a one click deal (or should never be).
You will definitely need to get in touch with the agent who had put up such listing, and if you are not too knowledgeable with the ins and outs of real estate purchasing, you also need to consult a lawyer for added protection. eBay has also published a useful guide about buying real estate. You can read it at http://pages.ebay.com/buy/guides/real-e ... ing-guide/
Hope this helps!