Red oak stumpage prices have been suppressed for the last year or two. However, I still know ssome sawmills who are paying really good prices for quality butt logs ($0.60-80/bd.ft.). More than likely, the price you receive and the price you want may not be close to the delivered sawlog price indicated above.
Seeing that you only have one tree, I'm not sure what kind of price you can get or ask for seeing that your tree is already down on the ground. My suggestion to you is to contact a local portable sawmill owner to see if he would be willing to purchase said tree. Or, you can place an add in your local newspaper.
Contact your local IA DNR forester for a list of local portable sawmill owners.
Best of luck!