Never really thought to ask before but just what could a person expect to pay a marina to launch a boat and raise the mast and then lower the mast and place it back on the trailer?
It depends on the marina, but it's in the hundreds of dollars anywhere you go, and the bulk of that cost will apply each way. As I recall, about 10 years ago, I paid a marina over $200 just to launch my 25, and another $200 to hoist it back onto the trailer, and I had to raise the mast and rig it.
IMO, the biggest boat you can trailer and enjoy is about 22-23 feet. The weight makes it easy to tow without having to use a monster truck. A half ton pu will do just fine. Even a mid-size suv can tow it. I had a C22 with a swing keel, and, with practice, could launch it, rig it, and sail away in 30 minutes, with my wife's help and no A-frame or similar device. It was so easy that I frequently towed it to a lake, launched it, sailed a few hours, retrieved it and towed it home. Later, when I owned a 25' boat, towing, launching and rigging was so burdensome that I wouldn't even think about doing all that for a few hours of sailing. The difference between trailering, launching and rigging a 22 and 25' boat is night and day.
When a boat manufacturer says his boat is trailerable, take it with a big grain of salt. If the boat is over 22-23 feet, it can be done, but will probably not be as easy as he claims.