I use BTZS tubes for 4x5 processing; they are easy and efficient. Chemical usage is 2-6 oz. of solution, depending on your agitation method. I use 6 oz. total solution, with D-76 at 1:3, so this is 1.5 oz. of stock solution. Pretty economical. I use semi-stand development for agitation.
The tubes are relatively inexpensive, less than $200 for a set. You can process one film at a time if desired, or up to 5 at a time.
The tubes can also be home made using black plumbing pipe. I have not done this, but it seems easy enough.