buying a live a board
There a a lot of boats that can fit that requirement. Recently cruising world did a review on great boats for under 15K. all were around 30 ft. If you don''t mind going slow the westsail 32 is a great cruising boat and liveaboard for around 50K. We had a nor''sea 27 that would be fine for 1, but only a 8 foot beam. Look for the widest boat you can find in that size, as wider boats give you more liveaboard space. As far as dock fees are concerned, call all the marinas in your area, get quotes, then quotes on insurance. fiqure 10% for monthly maintaince, although that figure will vary.
good luck. bob