Raffay, you need: Lens, camera, at least one filmholder, camera support, film and a place to process it.
$300 will get you (with luck) a camera or a lens.
But here's what you could do - get a lens, and then get an 8x10 GG back. Make two boxes of 1/4" plywood so one slides into the other - mount the GG back on the bigger box, the lens on the box which slides inside, use some velvet to keep the light outside and/or make some baffles. You now have a focuseable boxcamera, put four rubber pads on it (like an old Deardorff V8) and a table can be the support.