Purchasing parts from private parties

[Victor Michael <vmichael@enteract.com>]

P-P-P-P-Greetings,

Well, here we go.  You all recognize the phases of a new owner, I'm sure.
I'm looking to purchase parts from private party sellers and am curious about 
a few things.

What is the normal protocol for doing this?
Sending check or money order to strangers makes me [just a little] nervous.
Does the seller normally offer a guarantee on parts (radiator in my case, so 
far ;)?

Thanks in advance,

Vic