You might try a boat shop (such as West Marine), a plastics shop (such as
Tap Plastics), or a paint shop (especially one that supplies paint to
commercial painters doing car/boat restorations). Ace or other "retail
shops" are unlikely to want to bother with MEK (too few sales to justify
having it on the shelves/dealing with the 'special' shipping).
MEK can no longer be mailed and shipping it in small quantities is
essentially unrealistically expensive. California state regulations are
more restrictive on all hazardous products than just about anywhere
in the country ... but you might find it in Iowa ("Eye-Oh-Way") if you
look somewhere other than an Ace.
Handling/using MEK is not to be taken lightly and proper
ventilation is not just recommended it is required.
Personally, I'm still working thru my stock of Tenax and am
unlikely to ever consider MEK.
- Jim B. (who found MEK listed as in stock in a West Marine in Burlington, Wa.)