I, too, have a bunch of logs waiting to be milled. I try to keep a selection on hand for clients who have a creative idea, but don't have a log to mill. Most of my logs come from tree services who are interested in preserving urban logs (or perhaps it is because they can maximize their profits by avoiding a tipping fee at the landfill and getting paid for the log by me). After a couple of years, they start to go down hill, some species faster than others.
I always have more than I sell, plus there are logs here that belong to clients who delivered them but have not yet had them milled.
I am in the process of finishing up a DH kiln which should allow me to go through my stockpile. I can mill older logs, culling heavily, and what yield I get will be air dried and then go into the kiln. I currently market my milling services, the whole point of having logs available is to promote my milling. Selling kiln dried lumber will be a new venture for me, and offer a second income stream. As a custom sawyer; if I'm not making sawdust, I'm not making money. The kiln will be making money when I am milling, working on the computer, or even when I am sleeping.
I have a designated area where I store my logs. I don't really want to expand that area so I have to use up older logs, and push clients to get their logs milled. This year I instituted a storage fee of $1 per log/per month for client's logs. Hopefully I'll have time to mill my logs, business has been very good - my milling volume is up 29% over last year at this time, and a busy time of the year is coming up.