"my biggest issue is lack of people willing to take them in".
I feel bad saying this but . .. that's the very real and obvious problem. People can get a betta for a few bucks and choose from many any day they want. It's not going to be easy to place them all, just go to the ASPCA and ask them how easy it is to find homes for rescued pets.
I don't want to sound like a jerk, I do wish you the best of luck but you should be prepared to have a full house of every betta you take in just in case you run out of friends to put them on. If you are rescuing 6, be prepared that you will have 6 bettas possibly for a long time, that's all.
I have 7 and I am sort of freaking out because that is a lot of tanks. If I have to move I am screwed! Good luck though.