Some of the cheaper, closer places I've stayed in that I felt were clean and safe are Howard Johnson's (slightly further away, but nicer, more like a hotel, and still not too expensive), and Carousel Inn (right across the street from DL).
I've also heard from friends that Desert Inn & Suites is very convenient, clean, and roomy, plus they have (I think) refrigerators and microwaves, which might help to save some $$$ on food.
I would avoid Best Western Stovall's on Katella, we had lots of problems with things not being clean, as well as air conditioning leaks, etc. We really liked BW Park Place Inn, right across the DL entrance, but that one is probably close to $100.