We dived on the yacht monthly after an antifoul and then fortnightly towards the end of the annual period. Racing yacht needed a slippery bum. 60 foot took us (2 of us) an hour once it was dirty.

Generally mum did the waterline and dad and I did below the hull.

Winter was hard

Must add that the boat was penned at South Perth yacht club for most of the year but spend the three months of winter at Fremantle.

Fremantle Sailing club was far more for the clean all be it freezing cold in the middle of winter.

lots of things can influence the answer to your question - simplisitically - the more you use the boat the easier it is to maintain
I have a penned boat which i lift once a year for hull clean and antifoul + prop speed, i get a diver to clean the hull prob 3-4 times over the winter as the boat is not used as much- he charges around 150-200 per clean
If you dont use your boat regularly you will get a lot of growth on it - antifoul only really works if you use your boat regularly -
costs will depend on boat size,
a lift in and out is around 300-500 depending on club/marina, hardstand fees vary but around 20/40 per day -i usually keep mine out for a week in which time i can get everything done
antifoul is around 250 for 4 litres and for a 40 foot boat as an example you will need around 10L
There are also other things like anodes etc - not expensive - but it all adds up

You can do it all yourself - its not hard - just an ugly job :-)

 My boat is penned at Hillarys and barring any unexpected mechanical problem, it comes out once a year as Pelagicyachts said above. Last year I had 4 days boooked but they left it out for 2 weeks because they were in a shambles organisationally. They lift and blast off the hull, then I get them to do the anti-foul, propspeed and new anodes. I cannot be bothered doing all that prep and anti-fouling it myself but a lot of people do. I get the motor and leg serviced at the same time as the leg has to come off as part of the service.