(Just my opinion on how this ought to go) I agree with Pars.
I would keep this group buy/build to only amp boards and psu boards (with parts), and a separate enclosure buy.
Since in nature this is really a DIY project, those who cannot assemble an amp from stuffed boards, should really consider if this is the right project for them.
I know I am not planning to build any amps for anyone but myself, but I could stuff several boards for others and have volunteered to do so. Not sure if the other 'builders' feel the same way, or if they are willing to do more than stuff boards.
I know my time is limited, and I could not take the responsibility to build a whole amp for someone, and deal with the types of issues that a 'for hire' builder is willing to deal with. Considering he hopes to make a modest profit, dealing with those issues is part of the game when operating a small business.
All stuff to consider, as expectations management needs to be put into place here for non-DIYers, as well as defining what it is we are planning to buy.