Matt Haughey moved into a new home with a lot of deadbolts. Rather than carry around a jangling morning star of keys, he decided to re-key everything. It took less than a day.
I researched getting a locksmith to come out, but it would run hundreds of dollars in their time plus you can only re-key locks to a key made by the same manufacturer, and by my count we had at least three different brands of locks spread among all the doors. I could save money by bringing the locks to a locksmith's store, replacing off brands with a single brand and re-installing myself, or I could teach myself how to rekey locks using a ~$100 set from amazon that takes a few hours of practice to master.
He replaced three of the locks so all could use the Kwikset Smart Key [Amazon] system, the hero of the piece — about $100 all in.