Obviously finishing would fall on the customer to provide. There are several ways to go about this:
1) Go the Madisound route and offer just the drivers and crossover with cabinet plans. Crossover assembly as an option.
2) Sell just the plans and parts list for crossover, drivers, and cabinet. This would have the least impact on your overall effort.
3) Provide knock-down cabinets, or the option of just the front baffle with cutout(s) along with crossovers and drivers, as Parts-Express does.
4) Knock-down cabs alone with plans/parts list for crossover/drivers.
5) Possibly contract or recommend other speaker builders to provide the service much like Dennis did with you and the BMR Monitor.
As you can see there are an array of options for this. It all depends on your schedule for providing the DIYer any particular option.
Just my $0.02 worth.
-Ron