How do I pay?

How close to you does this seller live? If no shipping is involved I think Misstl has it right above. Plan to pick the speakers yourself and bring cash to his house after you make sure he doesn't live in a dicey part of town. If you like them after inspection/listening, help him load them onto your vehicle, then pay him and drive home. I’d like to see his receipt for them too from when he purchased them originally, just to be sure they are not stolen merchandise. Having had worked 25-30 years in Corrections, I can assure you there are an awful lot of crooks and con-men out there.

Mike

Quite simple, Don't get obsessed over 1 particular speaker for sale, Move on to another speaker or wait til another pair  becomes avaliable. 
Paypal offers some protection. I would never ever send a  cashiers ck for anything audio. 
I only use paypal

Yes if you live within say 500 miles, maybe you could split the drive  with seller, pay in cash. Seller has to give $100 for drive fees

Don’t do it!

Buy them in person or don’t buy them at all.