Log prices vary greatly dependig on quality. A veneer log may be worth 2-3 times as much as a good grade sawlog, depending on species. Low grade is worth far less.
30 logs is about a load of logs for a truck. You might be able to get them to come out and pick them up and grade them. They'll have a price list of what they're paying. You might want to go to the DCNR if you're looking at moving them to a mill.
If you're thinking about having someone come and buy some for a small mill, then you'll have to do some sort of advertising to get some interest. I know that some of the guys here on the forum look through Craigslist for stuff.
As for price, find what the local mills are paying. Don't go below that. The logs should be fresh cut. The longer they lay, the worse the price gets.