Yikes! What a thought!
However, if the unit does have bedbugs, the seller would be legally responsible to inform you of that fact.
I would suggest that you ask the seller to prepare a "seller's description of property" document which they sign and you sign. If you are fearful of bedbugs, ask them to add an addendum regarding bedbugs to that report. Then, if it turned out there WERE bedbugs, you could come back to the sellers and demand compensation.
Meanwhile, I would contact an exterminator and ask him/her how to eradicate bedbugs from an empty home. It might not be an expensive proposition, and if it gives you peace of mind, then do it regardless of what the seller reports.