How do you get "lack of knowledge" from my comment? Are you certified to ship hazmat by any chance? Having "lack of knowledge" = illegal shipments. None of them are lacking knowledge of Hazmat shipping, if they were they wouldn't be in business. DOT does not play around with Hazmat, and will fine you until your company is no longer viable.
When you live out where I live, you ship where you can ship, and pay what they charge. The first place you go is usually where you ship from. Hardly ever is that the postal office.
What you should do is understand the logistics behind getting you supplies that are described as Hazardous Materials. It takes certifications by a company, certifications of employees, and the responsibility always falls on the shipper. Get it wrong and you could face jail time, not just the company but the employee as well. All of these things cost money, and the cost of liability is high. Powder Valley does this as a specialty, so in theory it should cost them less to handle than say Midway, who offers it as an additional product. Powder Valley is also behind on shipments a little due to demand, but Midway has shipped everything in stock close to same day. I had to pay for shipping at both places, about the same price, but I've gotten my midway shipment a week before the PV stuff every time. It's nobody's fault, it's just being understanding of how things are different across different businesses, and how shipping hazmat adds complexity to a shipment of next to nothing. To a normal person it's "throw it in a box and send it", to the company it's more complex than that, and could include fines and jail.