I am in talks to by a 91 Civic DX and the guy mentioned he blew the main fuse and doesn't want to deal with it. Does anyone have a part number an autozone link or anything that would point me in the right direction. I would like to buy one and take it out there with me to see if that is actually the problem.

 

Maybe verify with him if he's speaking of the common "Main Relay" which is not a fuse, but is known to go bad due to cracked solder joints on the board, or one of the large fuses in the engine compartment fuse box. I'm not near my car at the moment but I'm sure there is pictures of it around. It's a 50amp fuse labeled IG.
Years ago some buddies and I spotted a yellow Si looking unloved in a yard. Owner said it wouldn't start. We agreed on $500. Put that fuse in and drove it way. Never popped again.