Kriaz8100 can you PM me your contact details.I can look for a used tank here.But chances are it won't be in much better shape thank yours.
The best bet is to get a used tank and get it cut open.Get the tank washed and prepared chemically then coat it with a solution that will not dissolve in petrol.Then weld it back and do a leak test.
Finding a new tank is not impossible but not at all easy either.You may have to take your search over seas.