sharing info on diggers to buyers????

I was wondering if anyone knows if ODNR or dept in your area gives out info on diggers to buyers??? The reason I am asking is because I sell to one person and this year I got a letter in the mail from another buyer in the area about selling to them this year, and how prices are down due to overload from last year ect ect!! How did they get my info and address if not through Dept of Nat. Res. ??? I dont agree with this at all and dont think everyone needs to know my buissness. Any thoughts....