A Mobile Trailer for $3500, including the Trailer, CoolBot, and AC unit
Pack N'Cool CoolBot Trailer Instructions write-up from North Carolina State. This is beautiful -- check out the lower left hand side of the website for links to detailed construction plans and budgets... So well done. I think we have been getting as many requests for trailer-coolers as room coolers lately, and this will certainly help a LOT of people.
Here is the link to their detailed plans: https://plantsforhumanhealth.ncsu.edu/pack-n-cool/