You need to price the rest of the chemicals, and read the finer print on how to reuse them. I just don't see it as being any cheaper than the 5 liter kit. I mean 5 liters is like 1.3 gallons. You get everything you need in the kit for half the price almost of the 1 gallon chemistry. The only saving grace is that if you were to set up a small tankline & either reused it & dumped or replensihed it, you could buy individual steps and stagger them as you needed them. You'll understand this maybe if you start using it like this, because from what I understand from the tech sheet in front of me, you still only get about a month out of working solitons of the first four steps, then you get 4 months for the bleach & fix which are always really oxygen & abuse tolerant anyways. It's the first 4 steps that are so fussy. If you can't keep them in airtight containers, you only get 1 WEEK for the first four. The fine print says that you need to process as much film at a time per run. They're talking about batch processing here....not stertching out the chemistry for a roll here or there. The capacity numbers are different for small tanks versus the full gallon as well. But to me, a one gallon tank *is* a small tank....
So, I just don't see the economics of it myself....reusing the bleach is a good idea for some though, and alot of labs are set up for this. We had a bypass valve put into our processor for this specific reason, but encountered problems getting it back into the tanks again eventually and having to deal with aerating the bleach as well.
Bottom line for me is this: you will most likely not save any money doing it yourself. You may gain more control depending on your setup & level of skill. if it isn't a PIA to set up your process, it will be more convenient unless your lab is next door, but you will not save money and you will probably never get it right unless you run a replenished line with control strips.
Incidentally that's 134 sheets of 4x5 per gallon of first developer, reversal bath, color dev, and pre-bleach. I don't have time to run the numbers on the bleach and fix, but it looks like you could get half as much or more out of them depending on how you're set up. BUT--that's 134 sheets in a ONE MONTH period in an airtight container. So, figure out how much film you shoot in a month in 4x5 and look at the cost from there in addition to the time, equipment etc.