I have bought 4 systems, I have built 20+ DIY exact copies, and I have had quite a few UC systems givin to me to play with, so i can tell ya first hand that I know a little what I am talkin about and you don't sound like you know at all....all of your "about" prices are not even close..there is no decent 500+gph pump out there for $50 bucks sorry but Mag drive pumps are amoung if not the best out there, UC changed to these from their previous pumps. I think Wayne pumps are the only ones rated higher for the application and they are really expensive. Duty cycles and reliability are critical and gettin a cheap ass pump is a step in the wrong direction IMO. Uniseals are twice what your puttin and I was buying 100-200 at a time and they are 3" not 1-1/4" and the cheap air pump and chiller are just cheap ass used gear pipe dreams.
13 gallon buckets are $11.00 and you have to buy 45 and go pick them up at that price. and honestly the exact ones that UC uses are hard as shit to find. There are a ton that look the same but the thickness, workability, and tendency to split at the hole is whole lot different. The cheapest I can get the lids down to is $12 and that was with me goin to a waterjet company and gettin them to nest 4 sheets of the same abs UC uses, so at 20 per sheet so that was a $880 bill for 80 lids.
I literally have 100's of pages and hours of research and sourcing every item in the kit and can tell you that you have to put zero value on your time and effort for it to really pay off.
When it gets right down to it, you will have between $95-$110 per bucket in the system and that includes everthing, pumps, seals, tubing, air stones etc... so for a 4 site, which actually has 5 buckets including the epicenter you are goin to spend between $500-$550 with no labor or time figured in at all period, hands down, been there done that many many times now and believe me my research was alot more thorough than just referencing some other thread of another farmer that didn't do the research or take the time to actually copy the system either IMO.
Tex