Look at prices for the MPP technical field cameras. They are often compared to Linhof in design, movements available and build quality. I think a nice MPP version V 4x5" usually can be had for around $500 with an older lens, or approximately the cost of a Tech III. Also take into account whether the lensboards look like they can be easily fabricated (best if they are just flat simple rectangular boards with no light trap or complicated cuts) so you can add lenses to this system, and whether it can take a rollfilm back, because you might not want to be limited to films available in 2x3 sheets.