I use Cervelle Merchant Magic. Not the most flashy system but it works. I love the fact that it automatically syncs/manages your bound book. We are approaching 10k guns and doing that on paper or another system would just be way too time consuming.
PS - If you want to come out to Tracy I can give you a demo.
Tracy Rifle and Pistol
7601 W 11th St
Tracy Ca 95304
For sales Questions please email Sales@tracyrifleandpistol.com