I do repairs like this all the time. It all depends on what the problem is -- it can be as simple as a sinuous spring clip breaking or a board (lumber or more likely, if it's broken, plywood or particle board) breaking or coming loose at a joint.

Either of these repairs run an hour or so.

I just find it tough to make a go of it to have to have an hour on the road, spend 20 minutes or so in diagnosis, then give an estimate to have it declined or "think about it." In other words, be prepared to spend $100 to $150 for repairs. If it's not worth that, be kind to your repair person.