I know that Fastenal can get acme as that is where I got mine. They don't list it on their website, but when I inquired about some 1/2 -10 single and they actually had it in stock at one of their Edmonton locations.
Not sure where you can get rack in Alberta... I just ordered some from Moore gear in the USA
3 x 6" pieces of pre drilled rack came to $268 including shipping. The rack was .5 x .75 20 degree.