NPS (Nationwide Pool Supply) is affordable & helpful! I first called the sister store on Boulder Highway, who pointed me to the NPS store in Green Valley closer to my home on Eastern Avenue. Alex (Manager) and Nicole were really helpful and happy to answer my 20 questions, since I was a new pool owner. After doing online price comparisons, NPS seems to be the most affordable for most items, especially for chemicals. They will test your pool water for free (just bring in a small bottle from the deep end within 45 minutes). I ended up buying my own test strips, so that I could test it more frequently at my own convenience.
Their website does need to get updated with their current store hours are: MF 7a-7p, S 9a-6p, and S 10a-5p.