Joe, I think the value is also in the plug and play aspect and that your guide will quickly get posted somewhere for free. One only has to look at the RIMS for dummies thread of any one of several dozen control panels builds here and they can build one for free. Some like Kal, Pol, and P-J have painstakingly documented their builds.
For those with little to no electrical experience, there are no reasonably priced plug and play alternatives.
I am thinking of some competitors:
1. Sabco RIMS Wizard is plug and play--but like $1700
2. Brewers Hardware has a NICE RIMS tube, but you still have to have a controller
3. Brewtroller and BCS can simplify a system design and are expandable
4. PID controls can be a bit daunting for the inexperienced, DIY RIMS for dummies tube
5. Johnson A419, Love, etc
6. EBC from High Gravity (kinda pricey for what you get IMO)
I was only skeptical that you could put a tube, PID, relay, control panel, wires, element etc and still make a few bucks at that price.
IMO, move that RIMS tube outside the panel, offer an upcharge for stainless parts and you've got something even at slightly higher than the $250 price point