I too pay for the PARI convenience of the 7% "HyperSal". I get it at my local grocery store pharmacy, along with all of my other meds. It is nice to not have to refrigerate it, but I pay a hefty "brand name" copay every month for it.
But you don't have to pay the PARI price tag! You can make your own at home. I grew up on homemade saline, from boiled tap water *gasp!* And I still only culture 2 strains of PA at 32 years old. Go figure. A very good friend of mine gave me this awesome hypertonic saline recipe.
To make cheap easy hypertonic saline at home follow these instructions:
Ingredients/Supplies
1. Sea Salt (without Iodine)
-you can find this at your grocery store
2. Gallon of Distilled Water
-again, found at the grocery store
3. 1 Liter bottle
-Look at your drugstore. You want one that is thick enough to hold hot water without melting the plastic and a tight seal.
4. Pot or measuring cup to boil the water
5. Measuring spoons (teaspoon) *note 1 gram sea salt is approximately equal to 1 teaspoon sea salt
For 7% saline you add 7 grams of sea salt to 1 Liter of distilled water. (technically you should also add 7 extra teaspoons of water to get exactly 7% solution.) Mix the water and the sea salt. Bring it just to a boil and then let it cool. You can even do this in the microwave for added convenience!
Store the bottle in fridge, tightly sealed
I used to make a new solution every week. It's very cheap and very easy. And if you want a stronger or weaker concentration just change the amount of sea salt. For example, for 3% solution use 3 grams sea salt in 1 liter of water. For 10% solution, use 10 grams sea salt in 1 liter of water.
And there you have it.