I'd probably be mildly annoyed but move on quickly. I've had so many bad experiences with secret Santa type gifts I just look at them as an opportunity to give something and not expect anything in return now. Maybe I'm just picky and hard to please. If I do get something I like its just an added bonus.

But in general yes, I think it's important to stick to price guidelines. I'm often guilty of going over which is probably just as bad as going under.