Large Sandstone Blocks?

[barilms]

I have recently found a dilapidated Sandstone block foundation from an old house in Eastern Ohio I will be harvesting them for use in landscaping. I am not a landcaper, nor in the business. The blocks are in good shape, old and mossy but still square and usable. The blocks are very large, they measure approx. 16x12x24 - some a bit larger some smaller. How much do you think each block weighs approx? How much can I expext to sell them for? I will be selling 75 blocks or so. Any help would be great, thanks!