If you don't mind limitations, you can build a big camera pretty cheap. Sliding box camera, make the ground glass frame removable so after focusing you slide out the gg and insert the film holder. Use plexiglass for the ground glass. If you are shooting landscapes you don't even need to build in that much slide in the boxes. I build my own film holders for my ULF cameras using komatex (an expanded PVC sheet plastic) and use double sided tape to hold the film in place. The tape stays tacky enough that you can load the holders about 10 times before you need to replace the tape. Sheet of powder coated .080 aluminum in the middle and a composite plastic called garolite for the dark slides. The only precision machining involved is the light baffle end to insure a smooth fit for the darkslide. Everything else can be cut with good home shop tools. A holder for something as big as 12x20 costs me about $90 to make.
The down side with the holders is the plastic comes in .5" sheets so the final holder is 1.080 thick and therefore the camera is not compatible with standard holders. But hey, when you can build 4 for the cost of one standard holder, who cares!