I'm another believer in having a lightweight portable machine for class. You can even leave it in the trunk of the car if class is weekly. I bought a Brother from Costco that held up well for about 5-7 years being carried from place to place, finally I had too many issues with the bobbin area and declared it unusable, a friend of a friend used it for a trade-in credit for a nice expensive machine. And then I found a similar one at the Goodwill for $30 still in the box and uses the same feet etc., so I once again have a portable machine.
On the other hand, I like doing all my work on the same machine for each project so I understand that too!
A friend of mine is giving me her old Bernina and we were looking at shipping options. I think it is much to awkward really for regular use but depending on the dimensions a wheeled cooler chest was one of the cheaper more secure options we found. We decided that we would ship it "slow boat" UPS, it still might be cheaper to pay for luggage on the plane, but then we would have to deal with it at the airport -- in which case a portable fold-down luggage rack from Office Depot was only around $25. My friend went to the Bernina shop and bought a shipping box from them that has the foam inserts and such.