I saw my rotting railings as a way to fund a new hobby. Since that project I've built a gate, a few planter boxes, fence repairs, a table with the scrap wood and a few other minor things. Enjoyment aside, my cost savings including the value of my vocational time would be reason enough but like you said I have specific cases that can't be bought off a shelf.
It is also difficult to get skilled labour to perform small jobs where I live so it is almost a necessity at this time.