Unless your ride them all a trailer seems like an inevitability one way or another. Are you not in a position to tow them yourself? I mean I'm all about the I rode mine concept but sooner or later it just makes sense to tow. Could rent a trailer and truck from youhaul and get it done for reasonable money yourself or as has been pointed out pay 5x the amount EACH. Or throw caution to the wind and hope all 4 make the trip under their own power and without forcing a tow half way there.

 

Give three to me. Your choice.

 

Or a one way rental of a Uhaul truck.

About $1,500 one way, 1,000 miles for a 20' truck. But, getting them up the ramp can be a PITA. Helps to find a load dock.