Something you could try is to canvas local businesses such as large trucking companies, road contractors, agricultural equipment dealers, etc for end of life chains to donate to your non profit. Purchase a large chain pliers tool (mine cost $65) and repair links and you've got a couple of days of entertainment--for you and the reality show.
I decided on 2-link ladders for my DK35 front R4's this year but balked at the $390 price (including tax). I had an old set of 4-link, v-bar ladders my neighbour gave me when they moved back to France. They were unsuitable for the rears because the cross links got completely lost in the tread. I bought DUO's for the rears.
2-link ladders would have worked for the rears but the chains weren't long enough to convert. But they were long enough for the fronts, with two cross links to spare. I had to shorten each cross chain by three links. The front chains made a noticeable improvement.
Another neighbour is a parts man for an AG equipment company. He built his free chains using their tool on a couple of lunch hours, and old chains from the scrap pile (all with the company's approval).