5x7 is a great format. But, it is a fair amount more expensive than 4x5. If I were going to go larger, I would jump to 8x10. More film choices, just as much a PITB as 5x7, but the contact prints!!! Amazing.
If you are set on 5x7, I have several Burke and James cameras. One mono (Grover), one wooden field (Watson). They need work but cheap to a good home.
tim in san jose