Do you know what region your contractor buddy was referring to? As of last year I was able to salvage a large number of tires for free in Tennessee. If I remember correctly, tire retailers are legally required to collect old tires from consumers for recycling/processing and to pay a small transfer fee per tire collected. Since we were offering to come collect the tires it was cheaper for the local corporate tire retailer to donate the tires to us to build with than to pay the usual collectors to remove them. Their used tire supply depended on how much storage space they had and when the last pick up was, so plan ahead and let them know how many you will need to find out where/when to get your tires. I suggest that you call your local tire retailers and see if this is the same case in your area or not.