Check with commercial industrial chemical suppliers.
You can buy drums of methanol for dirt cheap, that have certificates of purity.
To ensure you're getting a pure product, you can also buy a hydrometer for as little at 57.00 to check the water content on the spot. If the drum has more than .5% water, don't take it.
http://www.goodvibesracing.com/hydrometers.htm
The stuff I buy here in the states is certified to 99.99% pure methanol.
Once you use methanol as a roots blower fuel, you'll NEVER EVER want to even consider gasoline for anything but your tow rig (unless you have a diesel).
You did yourself a favor in getting the big blower. Slowing the rotors down helps with keeping the air cool, but Kuhl has been out of business for quite a while now and there's quite a few better blowers out (even for gas).
The imports have a HUGE advantage in gas, simply because they're running centrifugal blowers or turbos, and have the ability to inter cool the air. Roots doesn't have that ability, and as such it's hard to get a cool, dense intake charge on anything but alky.