Are you talking about the 25mm 5mL capacity one made by Tobecco? I've found at least 1 vendor who has those...in several different colors...AND on Sale. Have also found vendors who have the Supertank Mini 22mm with 4mL capacity, which seems to have been the first one Tobecco made. Or was there another manufacturer who made them and they're the ones you can't find?
Also, if you'll put your location under your avatar [at least your country]...people could hopefully recommend vendors who have them in your own country.