You make a fair point about having a work shop do your fuel system, then It becomes a reasonable price.
But the majority of people on here who have neat/powerful street cars do a lot of their own work or at least like to do a few things themselves, which is one of the best things about SAU. As you would know setting up a surge tank (even and undercar one) is not hard, sure it might not win you a spot in the Summernats Elite hall, but will do the job. for a true streeter.
Yes there are many people on here that are also chequebook racers/drivers so no doubt they will sell well, especially to the crowd who pay $500 for a plug and oil change.
I also agree with Trent, Sell the lid seperate.