How long's a piece of string? Depends on where the lift is & how big the boat is. Surveyors normally charge by the boat size. You'll find quite a variation too. The one man bands are often cheaper. Lift out/back again is charged by the foot & very much depends on where it's done. You can get a craneage deal by doing it over a lunch time & having the boat held in the slings. i.e. Lift out-> driver has his lunch while the surveyor does his thing -> lift in. If the boat can take the ground & the owners OK, do it that way between tides & save the craneage. Bear in mind the surveyor will need easy access over all the hull so may not work with a mobo.
Also see if the surveyor's up for a deal. Many will. I Be there when it's done or available on the phone & if there's anything major found you can save money by getting the surveyor to stop and not write up the survey. Needs to be arranged before hand though as some want to do the whole job & be payed for it.
For something like 26-30' a lift should cost £80 - £120 each way unless you're on the Hamble where it will be more. Last servey I had was on a 26' & cost around £250-£300 from memory but that's 5 years ago.
Just be aware that if a boat is being taken out of the water for a survey it is best to ensure it is out of the water for at least a week to dry out before the survey is done. Moisture readings are only accurate after the boat has dried out.
The important thing is to get recommendations for a good surveyor so tell us where the boat is and you'll get some.
I bought my boat in Plymouth (300 miles from home). I rang round a few and it varied from £350 to £500 but the attitude and friendliness was very variable. I opted for the £500 and it was amazingly thorough and the guy is rightly recommended often. A cut price survey may not be the cheapest in the long run.
Survey lifts vary from place to place - some will just hold in the slings for a couple of hours at reasonable cost but they won't like it during the winter haul out period.
Survey cost depends very much where you are. We paid £900 for a 41' boat in Hamble. £500 for a 38' boat (the one we eventually bought) up in Scotland. It seems like a lot of money, but the first survey saved us buying a boat that would have cost us £20k or more to put right.