It's cheap. You can get it from hparts for around $50 iirc. It's a little relay in the driver side footwell right behind the steering colum.
Before you buy it, you can just pull it out and try to resolder the points if you wanted before you shell out some cash
It's a pretty common issue for our ludes. Just search "main relay" in thread titles and you'll find some juicy threads for you. I think there was one with pictures even.