One point is that the beam and height of the boat on the trailer make a whole lot more difference in what it will cost you than does the length. Height limits the bridges that it can go under, and if it is too tall can make routing extraordinarily difficult (which means a lot more money). Width affects what roads it can go on also and, again, can limit routing. In fact if it is too wide it cannot be hauled at all (which is why you never see a 30' wide catamaran being on the highway).
Less then 12' wide, $4 a mile or so, Less then 15' wide $7 per mile, Over 16' wide $20+ per mile. The miles they use are longer too, as they cant just drive everywhere. Also if from the bottom of your keel to the top of your cabin is over 13' high, then additional money too
My answer would be "it depends". When are you looking to move, size and weight. In the spring, you will get cheaper rates as many trucks are hauling boats north and dead head in the northern climes. If you are talking right now...well good luck. Expect to hear from $6500 and up, once again..size and weight.
A few movers I know of: Friends have used, or I will be using.