I received a letter in the mail yesterday from a purchasing group called "United FFLs of America" offering a free membership.  Best I can tell from poking around on their website, they seem to be a new group that someone is trying to put together.  Anyone have any knowledge of, or experience with this group?  

Thanks in advance!

I have not heard of them.   I looked into some buyer groups a few years ago.   As I recall, I was not impressed with them and not qualified.   I don't remember if it was sales volume, minimum purchase requirements, B&M requirements, or some combination of the three.
This one seems to have none of that, and even explicitly says it's open to home-based FFLs.
Application does ask if home-based or not, and they want sales volume.