I've bought dubia from dubi deli before. They gave me 15 live, healthy, young, ready to breed, female roaches when I only ordered 10. Then I ordered their bulk special for 1/2 inch roaches just last week and received more than I expected again. Overall, I don't think they're going to cheet you and do a fantastic job breeding healthy roaches. Most likely if you get dead roaches in the mail they would have died in transit from poor handling. I haven't had experience with their customer service in the event you do get dead roaches, but I recommend them.
Also they ship them to you in a burlap sack, I suggest you keep the sack and put it in the roach enclosure, when you need to raise humidity spray the burlap to get it wet. The burlap will ensure it doesn't get too humid and start mold growth. I used to have problems with keeping humidity up while also not having mold. Since putting the burlap in I haven't had any mold whatsoever and my humidity has remained between 60%-80%. If you're diligent in misting the burlap every other day or so you could probably get away without water crystals or wet food. As my roach colony is now I only have to disturb them 1 time a week.