Chris,
If the shipping weight, including packaging, is 150 lb or less you can ship it by a delivery service such as Fedex, UPS, etc. Heavier packages or packages larger than a combined length plus girth of 165 inches must ship by freight.
For freight shipping, I had good luck with freightquote.com. They are freight brokers who deal with many freight carriers. I found them to be very knowledgable and helpful, and I thought I got good pricing from them. Their discount was better than I could get on my own. Shipping costs weren't too bad, but I had to pay an extra $60 fee for a lift gate at the shipper's end since they didn't have a loading dock. I was shipping business to business, but there would have been another fee if either end was a residence.
If you are checking freight costs, be sure you know what freight class is being quoted. Higher classes are supposed to represent a higher degree of handling difficulty and of course a higher cost. My shipment was based on freight class 110, and I was told this is appropriate for tape machines. I specified nothing be stacked on top of the machine -- I don't know if that is part of freight class 110 or not.
Be warned -- the carrier's limit of liability for used machines is only $0.10 per pound no matter what value you declare unless you specifically buy and pay for insurance. (So if your Studer A827 24-track is destroyed, you'll get less than $100 back!) Insurance is expensive. I paid something like $45 per $1000 of coverage with a $100 deductible.
The shipper blanket-wrapped and stretch-wrapped the machine to prepare it for shipping. We could have added styrofoam boards for more protection, but didn't. I decided to ship it on it's own casters as a roll-on rather than palletize it. The only damage was one caster that was ripped from the bottom and mangled. In hindsight, I think I was lucky that nothing worse happened.
I also shipped another machine using "The Packaging Store". This is NOT the UPS store (who can handle grandma's vase, but are utterly clueless about packing tape machines). The Packaging Store is a franchise company handling business machines, antiques, fine art, etc. The one I used was associated with Parker K. Bailey in Maine. They handled everything and were outstanding. I had them crate the machine in a wooden crate. Crating was expensive and added a lot to the shipping weight, too. We discussed using a triple-wall RSC (aka "corrugated box") instead, but I don't remember why we didn't go that way. As I recall, crating costs were around $5 per cubic foot. I have heard estimates in the range of $5-10. The machine arrived in absolutely perfect condition.
Another full service company is Craters & Freighters. They were recommended to me by several people, but I haven't used them. They may be worth a phone call.
The $600 Mayflower Transit deal sounds like a real bargain! When I was investigating, I checked with the moving company we use. Even with our corporate discount, it was going to cost well over $1000 plus insurance. So I gave up on movers as a possibility. Maybe I gave up too soon!
Jeri