I shoot 4x5 for around a dollar a sheet (it's probably more now, I haven't bought any this year) on Fomapan/.EDU Ultra. You can shoot 8x10 for barely more than that if you use X-ray film.
From what I've seen, you can't even buy the glass to coat for less than that. Emulsion making, hand coating, glass plate, and especially wet plate is its own pursuit -- not an economy measure.
If you're after cost savings, get a 70 year old Graphic View, a couple film holders, and a box of .EDU Ultra 100 and shoot two to four frames on a trip out. You can still take half a day to do it with large format, and wind up with much more consistent and successful results than with anything homemade.
I don't know if Ilford cuts their Ortho 80 in 4x5, but you can get X-ray recut to that size for about the same price as .EDU Ultra (or cut it from 8x10 yourself under red safelight so as not to pay someone else to do it).