Need help with repair advice before I buy a possible POS!

Hey guys, I’m needing a little advice before I get in over my head. Any help would be greatly associated. I’m going tomorrow to look at/possibly purchase a 2001 325 Trail Boss. It’s clean and appears to be a very well taken care of quad. The owner says the chain needs to be replaced, and the trans has to be dropped to do that. I went to the local cycle shop, and they said the trans doesn’t need to be dropped, and it’s basically no big deal to replace a chain. I’ve never done it, and I don’t wanna buy this thing thinking that I’m getting a great deal on it, and end up having to sink a lot more money into it before it’s done. The owner says that it will move forward but makes a loud noise, says he had one do it before and the chain was stretched and it was doing the same thing this one is. He says it will run fine in reverse and never make the slightest noise. Supposedly everything else on this quad is perfect and he has a clear title and I can get it pretty cheap. Is it worth messing with? Is it really that simple to replace the chain, and does it sound like that’s what’s wrong with it? I’m sure the answers are somewhere on this forum and I tried the search function but didn’t really come across the same thing. I’d really appreciate some advice on this as well as what to look for, etc, to make sure of what the problem is before I buy it. Thanks in advance.