Oh, it doesn't take a genius to operate bear spray. Best time to buy is the spring and early summer when prices are lower and supplies are large. You can buy the 8.1 oz Counter Assault at the Army/Navy in either Kalispell or Whitefish for $34 no tax. Right now the supplies are limited and just the large spray is offered for $44. You cannot take it with you while traveling with the airlines, so I usually sell it for $20 or give it away when leaving the area.
It fires an orange colored mist 30 feet. Realistically, you are gonna need to bomb the sucker from 10-15 feet right in the puss as it lasts only 7 seconds. High winds are a problem in both Wyoming and Montana, so if that's all you are carrying then you will need to use it up close. Most people will give it a quick 2 second spray, but you need to use bursts of 3 seconds minimum. If that doesn't work, hopefully you have a weapon.