For a single CD, $35 is about tops, but that's only for the very few at the tip-top of my list. I could go up to about $35-40 for a double or triple with the same caveat. I don't really buy many box sets, and never ones over $60 or so, so I can't say about that. Same with vinyl, almost never buy it and never drop much when I do.
I think the most I ever spent on a single disc is about $25 for Joe McPhee's As Serious As Your Life. I paid $45 for Braxton/Santa Cruz. I also spent $66 on the two volumes of Ran Blake's Painted Rhythms. Generally, though, I'm a deals man and try to get CDs in the $3-15 range. You'd be surprised how things fall in your lap if you wait, like with the two Tony Oxley CBS CDs I pined after for years: I got both for $10/free shipping.