Here is the link you need: https://www.pneudart.com/index.php

They sell darts and guns.

As stated, you will need to get the drugs from a veterinarian and a lot of drugs used are controlled, which means the vet will not dispense them to you. Possibly where hogs are concerned, you might be able to get a noncontrolled tranquilizer from your usual vet if he/she knows you really well. However, I wouldn't trust a wild animal with just a tranquilizer to not "wake up" and bite you if you are not careful.

As far as transporting them, why not just have a trap that can be loaded on a trailer (flatbed, horse, etc.) and just haul them in the trap without drugs.

I am a vet, so if you have any other questions, email me direct as I may not check this again for awhile.