get an engineer to design your enclosure. keep the subs you have (effectively, those are free at this point). once you have your design done by an "ENGINEER", then take the design to a local cabinetry shop and ask one of the guys making cabinets if he could build this exactly to spec in his spare time on the side. If he says yes, get a quote. It's likely less than 250. most cabinetry guys work for beans and they do accurate cuts and alignment very quick. they are normally the equivalent of a "box builder" that has been doing boxes for 200 years.