I don't know where you live, but here in northeast Pa, I have access to crushed limestone that is used for making white mortar. I use it for making crushed limestone loads. I get it at a brick and stone supply yard. Before I got the sand, I made my own by crushing chunks of limestone which achieved the same results, but a little labor intensive, even though limestone is relatively soft.
How much are you looking for? I can mail you a small bag that would fit in a mailing envelope for the cost of shipping if you can't find what you're looking for elsewhere.
Don