Coastal Tool has the DeWalt D180004 Door Lock Installation Kit for $27.50. It may look like a medieval torture device but it’s a godsend when installing hardware to fresh door installs. For just under thirty bucks you, too, can get your doorknob to work without a string of profanities.
The kit allows you to drill the holes on the front and side of the door while maintaining alignment. It uses a simple clamp to hold it on the door and comes with the needed saws (there are three different kits for different doors and locksets). It’s mostly made of high-impact plastic so it won’t break the first time you drop it — maybe the second, but not the first.
Door Lock Installation Kit – D180004 [costaltool.com]