Thanks everyone for your suggestions.

So far Greyhound looks like the way to go at $52.80, if I can get the shipper to bring it to the station.

According to the USPS web site this is too big for them. The dimensions are

The weight is 76 pounds.
LT. 68inch
HT. 32 1/2inch
WT. 22inch.

Post Office site says max weight is 70 Lbs and that the maxcombination of length and measurement around the widest part can't exceed 130" so I guess they are out of the question.