At the shop, I used to work at we did a lot of short-run specialty decals for the aircraft industry in-house, and I would still outsource this all day every day unless there wasn't anything else to do. Jobs like these suck up way more time than you think and a wholesaler's price at these quantities is less than your actual cost of time, materials, and ink. Instead, you can make 30 to 50% by placing an order and continue making money in your shop focusing on more profitable jobs. There is one caveat, if you can get the same price each that you charge at 300 for the 8000 order, I'd probably be all in time permitting.
If anyone does go the wholesale route, read the fine print and educate your customer. The wholesaler we used had a policy that 10% over under was considered a complete order.