You can go to Home Depot and buy matching sets of deadbolts and handle sets that are keyed the same right off the shelf. They typically ship in groups of 4, so you can easily do up to 4 matching doors with no rekeying needed. The "keyed alike" sticker will be on the packaging so all you need to do is find 4 that have the same key code and you're all set. This will also give you a total of 8 keys so no need to worry about making copies, since copies don't always work as well. I prefer Schlage to Kwikset. Source: I used to work at Home Depot and now have been doing apartment maintenance for several years.
