Amazon
If you at home and need stuff this is the place to go. Great prices, great services. Just remember you may not be buying directly from Amazon but one of their many vendors. Try to buy directly from Amazon because their shipping and return policies are unique to the industry. Amazon will jump through hoops even when they are held up against a wall. If buying from one of their vendors check the shipping policies, some follow the Amazon philosophy of for a dollar amount it ships free, while others bang you hard for shipping to make up for their low prices.

Walmart
If on the road, a good thing, a Walmart may be available to you. Sam Walton, an avid camper, had extended an out reached hand to his fellow enthusists. A lot of Walmarts allow over night stays on their property, "boondocking", along with security checks from the store, cozy and cool. There are some stores that can not offer the over nights due to local camping parks petitioning against the policy, everyone needs to make money, what a shame. They carry a supply of RVing accessories, a small supply but a supply none the less. I broke a septic tank hose and they had one on the shelf. Try to find that at most of the other department stores and you will be disappointed.