Funeralman is right about only getting a few doses. The first time I went was about 7 years ago and they sold me what seemed like a lifetime supply. I must have spent $700. I think I had 4 1/2 vials. A couple of those vials expired before I could use them. However I did do a few injections after the expiration date but I could see the effect lessen the older the medication got. Also you might find that you can cut back on the dosage a little and get the same results, stretching the medication a little farther. I cut mine back around 4 units with the same result.
For use on the go you can draw a syringe, leaving the vial at home, and take it with you in a small insulated bag with an ice pack. Take the syringe in with you and inject before you begin like Notsomuch said.