You may be able to find dextrose at a bulk food store in the sugars section. When I found it, it was labeled "corn sugar" I think, with dextrose in parentheses.

Also, dextrose candies (the pressed powder kind like Sweetarts and Smarties/Rockets (depending on where you live-- and NOT Canadian Smarties, which are chocolate candies), this kind: http://www.candywarehouse.com/smar10cas.html.

I use dextrose exclusively because it's so effective.

It wouldn't be a bad idea to search the CKD forum for dextrose, since it has been discussed thoroughly there.