I'm a former F28R owner--a boat that I really loved, but sold to be
able to afford a cruising catamaran. I did like the shoal draft
capability for nosing into shallow coves in Puget Sound. The mast
rigging setup and launching is really pretty manageable and well
designed, and works well for all sizes of F-boats. I even did it solo a
few times, though it's easier and less stressful with a helper. Fuel
capacity was never an issue with a parsimonious 4 stroke Honda outboard
and two gas tanks which fit neatly in open lockers under the cockpit
seats. You definitely should be able to find an F-27 for less than $55k
if you're willing to do a bit of reconditioning.

While building an F-boat is doable, and many have done, don't
underestimate the amount of work required, and the possibility that
once you're finished you may have trouble seeing past the things you
wish you had done better. And while it may be an advantage to spread
your costs out over time, you probably won't end up saving much over
the cost of a complete boat.

Best of luck with your decision(s).

Aaron Tinling
s/v Sweet Destiny
www.navagear.com - the tools and tech blog for sailors