If you're buying from a "lot" then usually they'll have that done for you. If it's a private seller then it's up to the buyer as part of the registration requirement at the DMV. We've had a situation before, the seller we were buying from, has agreed to get the emissions done prior to the sale. Maybe this is an option for you. Discussing the cost of the testing was also a part of that conversation. For our situation it wasn't so much the cost of the testing but the time to get it done. If you're a serious buyer I don't see a situation where the seller would refuse such a request, unless of course it won't pass.