Dishwasher detergent for hard water-how to save $

The last several months we've been experimenting with homemade dishwasher detergent.  Our water is too hard to do 100% homemade.  It's also too hard to do 100% dishwasher detergent from the store.  So what do we do?  We have 3 things we add to every load, ok 4 counting the Jet Dry (but a generic) that we add every few months.  Here's how we do it:

Homemade Dishwasher Detergent:

1 part borax
2 parts baking soda
Put in a container and mix up.  I use a Country Save Scoop (probably a 2 Tbs scoop) and fill it halfway with this mixture and then I add

Cheapo Dishwasher Detergent-I'm talking the cheapest you can get-dollar store, Walmart, wherever

I put that scoop in to the closing cup and then add

Lemishine (I just add a little-the stuff is expensive.  We go through one container every 1-3 months)

Then I close the cup and turn it on!  I don't do automatic dry-I always turn that off.  Our dishes always come out sparkly and clean!  We're saving a fortune on dish soap because the borax/baking soda mixture is cheap and when we only use a little of each of the other two we only have to buy those every few months.