My dog keeps peeing in her crate...?

I have a 3 year old Weimaraner. She's food obsessed, so when we're gone or sleeping, she can't be let out of her crate or else she will dig through the trash, go through the pantry, or even jump all fours on the table. Recently she's been peeing in her crate. It's not from drinking too much water, and it's not because we don't let her out often enough, because we do. She pees in her crate 1 - 3 times a week. When we got her from the Humane Society, she wasn't completely potty trained. She never really became completely potty trained, but we don't know why. We thought she had a urinary tract infection when we first got her, but the vet told us she didn't. We haven't taken her to the vet because we are afraid it'd be too expensive for them just to tell us to let her out more often or not use a crate. Please help!