YurtGuy, I wish you luck and am happy to provide any advice and experience I can. I speak "heavy-duty sewing" and will help if I can. There are a couple of us on the site who sew more than recreationally.
To All: That said, comments about $400 5-ton bed covers strike a nerve with me. Skip the below paragraphs if you wish...
First: At $400, if they're not dry rotted, I say buy a pallet of them and sit on them! (In a climate controlled space.) If that sounds expensive, I can honestly say it's still cheaper than tooling and spooling up to make the same number.
Somebody once asked if I could make him a $400 HMMWV top. I said: Yes, but...does it have to FIT?
Speaking from experience:
I've had many people ask me to make trailer/truck/troop/cargo covers after seeing me sew HMMWV soft slant backs. I can tell you that $400 is impossible, for materials alone. Double it if the person doing the patterning and sewing expects any $$ for their trouble. Then add that amount in again for machine upkeep and other incidentals. Luckily, YurtGuy has machines. Even so, for those who have not done it, working with material that large is tedious. It is a challenge to handle the weight and bulk of several yards of material while trying to sew a straight line where you want it.
For all the sources of Mil-Spec vinyl I know, for an M54 or M932 the vinyl cost alone is more than $400, not including the fasteners and thread. I managed to find some medium weight PVC mil-vinyl two years ago at a good per yard price but had to buy 200 yards (truck freight =$$). All but one source of heavy duty MilSpec vinyl I know of has 100 yard minimum and another 200. The one that sells by the yard ($35/yd) is very slow to fill small orders. I searched for YEARS for sources that would sell mil-spec vinyl in less than full-production run lots (40' container load). Also bear in mind a full roll of MilSpec vinyl weighs over 150#. After taking delivery and horsing oneof those around, I'm done for the day.
IMO, it would take proven patterns, excellent machines and skill, bulk purchase of materials and perhaps some light automation to make fairly-priced covers under $1000, and one would need to sell dozens of them.
Can it be done, yes. Do a FEW people do it, yes. Is it straightforward, with an outcome ($ and satisfaction) that makes you feel like you didn't throw your time away, debatable. I don't see the number of military cover vendors INCREASING. (Not good ones. Compare a Blue Ox Tops' HMMWV 4-man top to a SECO top and the difference is noticeable.)
I'd love it if more talented cottage businesses stepped up and began producing custom covers for our vehicles but it is something you have to want to do. It isn't a good business model. One has to WANT to do it. Again, if I can help with advice and vendor information YurtGuy, I will.
Sorry for what probably sounds like a rant to 99% of readers. I guess I'm sensitive after running all the numbers involved in starting a business. I'm sticking with my day job. My sewing will remain part-time.
Bulldogger