John,
I charge $3.75 per loaded mile on any dedicated runs these days. 688 miles = $2580.00
I would consider taking the $2580.00 then subtract what you and Stacy have been paying in air fare to Houston, then haul it for that.
That said, the buyer can probably find a much cheaper rate using uship.com and finding someone looking for a backhaul, or going with an equine transport company that is putting together loads.
dang i didnt know freight had went up that much.