We have a similar situation here. My parents make Kahlua using a recipe very much like Ron's. We can't buy bottled grain alcohol in liquor stores in Manitoba (and perhaps not elsewhere in Canada, either?), but it's available in North Dakota so we often pick up a bottle or two of it to take home with us when we visit the U.S.

If you absolutely can't find grain alcohol, you can use vodka as a reasonably good substitute, although the grain alcohol is the best.

Cheers,
Rob