Here are the options I can think of.
1. UPS freight ground service: call 1-800-333-7400 and speak to a Customer Service Representative. Tell them the package will be crated, weigh 50 pounds, and have dimensions of 90 x 12 x 36 inches
2. US Post Office: $108, if not too large for them to take. This is the maximum oversize rate for parcel post
3. transport by a freighter (you know, a truck). Approximate cost: $300
4. transport by Greyhound bus package express. Approximate cost: couldn't find anything on their website. Maybe you can or call them at 1-800-739-5020.
5. see if anyone posting on hitchhiker forums are going your way. Here is one http://rideboard.digihitch.com/