My advice is check the online dubia vendors and then price accordingly depending how fast you need to get rid of them. I personally just sell my surplus on Craigslist for 100 any size for $15 and adult females for $1 each. I only do local meeting as I don't want to mess around with shipping and all that fiasco.
You check places like Dubi Deli, BuyDubiaroaches.com, Kimbrell's Cold Blood? Those are the 3 that come to mind. I guess it really boils down to how fast you want to move them and how much you feel they are worth to you. Like I said, I just sell mine for $15 per 100 any size and $1 for females on my local Craigslist. Even at that price I sometimes get undercut by other people doing $10 for 100. Again I guess it boils down do you want to get rid of them for something or keep feeding your surplus which in my case got expensive as they just destroyed anything I put in the bin.
I got a large group of mixed roaches from AB Dragons for $64 shipped back in September. Was enough to get a colony started without feeding off more than a few of them.
I can second ABDragons. I usually purchase them through Amazon. My most recent order just came in: 2000 small nymphs for $100.00 plus $7.99 shipping. It's freezing cold in my area so the seller directed the post office to hold for pick-up, even without any intervention from me. They've done right by me and will continue to get my business until my fledgling colony can support itself.