Are you talking about actual "effect:Gate" potions? They are vendor bought for about 1000pp
http://wiki.project1999.org/Vial_of_Swirling_Smoke
Shaman can make potions to port to Everfrost and Innothule, for around 300-400pp per charge, depending on their skill and failures.
http://wiki.project1999.org/Potion_of_the_Swamp
http://wiki.project1999.org/Potion_of_the_Frost
There is also the lizard blood potion which is an instant port to Cazic Thule, dropped from an NPC in the very same zone
http://wiki.project1999.org/Lizard_Blood_Potion
Finally, the easiest, cheapest (if you don't count lizard blood potion) and most convenient port of them all, the leatherfoot raider skullcap is an instant port to West Commonlands. It is rechargeable with the usual trick of selling a fully charged one to a vendor, selling the used one, and buying them both back.
http://wiki.project1999.org/Leatherfoot_Raider_Skullcap
Good luck.