It should be relatively easy to find 90% Iso Alcohol in any pharmacy or drug store. The other 10% is water. I would give that a try. There is also 70% commonly available (perhaps labeled as "rubbing alcohol) but I'd try the 90%.
Iso Heet (sold as gas line antifreeze) is 99% iso alcohol according to the msds. The other 1% is a "proprietary additive"; which could be anything.