Most of them can be found at any hobby store that carries Aerotech stuff, some need to be special ordered from the manufacturer.
BTW - their site is www.aerotech-rocketry.com
https://www.vforcerocketry.com/motors.htm I don't have a huge selection but I encourage you to compare my prices. Honestly I want to avoid the whole HAZMAT thing so normally only ship the mid-power motors that can to USPS Ground. I have made exceptions though, I just hate having to charge that huge extra fee.
Yes, I would say it is never more than 2 days out of date. There are only some occaisions where I may sell the last of some items in person or at a launch and the inventory is not updated until the next day. My motor inventory is also partially driven by what people ask for (If I dont stock any XYZ and no one ever asks me about XYZ then I'll be less likely to stock some of that.).