Hmmm... If it's, like theuglyorgan says, a life-changing experience (and that only happens once in a few years) up to 40 bucks. Bare in mind; A CD costs about 25 bucks here anyway. Usually I try to stay under 20 bucks. I buy records moste of the time and they are a bit cheaper than CD's for some strange reasion.
Having said that; I would only spend 40 bucks on a record, never on a CD.
My priciest CD ever was about 28 bucks, being Des visages des figures by noir Désir. The record would be about 50 euro's which I think is insane. The CD wasn't available any cheaper, wherever. Then I got to the Lowlands festival and I found a pile of those CD's for 10 bucks