MSI has a 250 dollar socket 2011 board that can have 128GB. I'm sure there are others, particularly with 2011 sockets, due to having 8 memory slots (2x4 channels).
Just out of curiosity, what do you need that much ram for?
I am doing a comparison to the CoreMC Gen3 tower. Trying to make a concept for cheaper. so far I am 18K cheaper than their price but that might dwindle if I can find a compatible Mobo