I purchased Lemi Shine Machine Cleaner directly from Lemi Shine. I simply signed-up for their email offers via their website, and then when they offered free shipping (if you purchased a certain dollar amount) I stocked the various Lemi Shine products that I like.

@posskat, do you have Canadian Tire in your part of Canada? They have it.

Here is a link that might be useful: Lemi Shine - Canadian Tire

Yes, straight citric acid powder would work, but I wouldn't use it. It would not contain buffers (these regulate pH to keep it from getting too low) and corrosion inhibitors (these protect the metal parts of your machine).

Big LemiShine fan here. I live in an area of really hard water too, and the product is amazing!
Washer directions are on the package, but yes, add it and let the machine sit with water in it for a while, then drain.
As to how often to use it, I'd follow the washer manufacturer's recommendation for cleaning.
Best of luck in finding it!

yes, there is a canadian tire here! duh! i was in the states and all i could find was the dishwasher powder, so i got that. i w/stop at canadian tire today--thanks for that! i didn't want my machine to even start to get the buildup, which i'm pretty sure is what reduced the cleaning power of my old machine....i'm using the machine now, and i need to get it more level, so the door won't swing open so much, as it's located in a hallway. vibration isn't too bad. so far am loving it! w/do a real review when i get a few miles on it.

Miele sells a washing machine descaler that's pure citric acid, according to the ingredient list.

@posskat, Calgon makes a product to prevent hard water buildup in washing machines. Not sure if it is available in North America but it is very popular in Europe. I get the impression that Lemi Shine or citric acid are to be used to remove buildup. If I had hard water (which I don't) I would rather use a product to prevent the buildup in the first place.

Here is a link that might be useful: Calgon Water Softener

@posskat, I've seen Calgon powder version at Wal-Mart and Loblaws stores.

i w/check that out, as we do have lots of calcium in our water; it's very hard water, but at least there's not yet any buildup on the machine!

Thanks for the tip about Calgon water softener. My local Walmart carries it, so I'm going to give it a try.