How do I pay?

+1 elrod

I'd pass on this deal.

If you must do it and can't do it in person, postal money orders offer some protection.  Crooks know that the feds will come after them if there is fraud involved and won't accept them. Ditto using postal mails to deliver it. Of course this guy might just be dumb and then you have nothing but a hassle on your hands getting the feds involved. My advise, don't do it.

If you have good feedback, it is reasonable for you to ask for him to ship the speakers prior to your payment. I have done this successfully in the past.

I'm going to echo what others have said.  DON'T DO IT!!!  There are plenty of speakers on sale from sellers with feedback.  Be patient.