I built a dinghy last year (stitch and glue). Just about 8' long. Rows great and sails well too. Here is a link to my "building blog". It was a fun project, but probably not any less expensive (overall) than a fair RIB.
I've got a 27' Catalina. I do have room to put it up on the foredeck, but it's HUGE looking and acting up there. No single-handed deck-sweeping tacks with the big genoa though.
Usually I tow it, or put on davits on the stern.