You need to get Permaguard only. All you need it a tablespoon in container of drinking water. And you only need to change it out every 6 months. My hubby puts a bit more in the container every 10 gallons or so. The DE needs to saturate the water to give the best benefits. So as you see, you don't need much.
And yes, the Borax in your laundry room is what you use. Again in your drinking water to saturate.
Maybe someone would be willing to go in on some DE with you. I think the last time I got a big container it was less than $20 including shipping. The cool thing is you can give it to your pets too, as well as rub it on their skin if there are any pests. It won't hurt them at all.