Costco has the NeilMed Sinus Rinse on sale for $15 after $4 instant relate. It's only available in stores. Comes with 250 salt packets and 2 bottles.
Normally if you buy 100 salt packets only in your local drug store, it's $15.
As an ENT who recommend this product to patients regularly, I do feel it's a good remedy to be used with allergy medications. However, it's not a true sinus rinse unless you had sinus surgery. It's really a nasal irrigation and helps rinsing out all the crusts, dirt and allergens that build up throughout the day.