In my quest for an affordable, but excellent, oven - I also came across these folks. I wrote them a note asking about references, guarantees or anything else they could offer to build my confidence. The reply said:
"If you have checked on wood fired pizza ovens this is one of the best you can see on eBay all customers are happy with the oven
Best Regards Randy"
I was not personally satisfied with the response and I moved on.