Guinea pig help... vet visit?

Ok so yesterday my guinea pig had died. I have 3 other guinea pigs and I'm afraid they caught there disease. One of them seems fine, the other is making this weird congested sound, and the other seems to lose its squeak. And because 1 vet visit is about 50$ and we don't have much money since the economy I was thinking I could just bring one of them (the one making the congested sound) and talking to the vet about what illness my guinea pig had that died so they can figure out if its contagious or not and what are the symptoms. Do you think this is ok since we really dont have enough money to bring 3 guinea pigs for a vet visit...?