Yes, exactly. We've gone from buying stuff at WalMart or BestBuy or whatever (with the associated marginal costs of gas, taxes, etc) to basically getting just about everything from Amazon. Small electronics, appliances, office supplies, etc. For anything over $50 or so I do compare prices with other online places, but more often than not Prime usually wins out simply based on the free shipping. For niche-ish things for example Monoprice will usually beat Amazon, but for most smaller purchases that are not immediately required, Prime has paid for itself many times over, especially considering my consumption of their member videos over my Roku.
I've really loved Amazon's "Amazon Basics" brand. Lots of cables available at very reasonable prices, simple, frustration-free packaging, and always Prime eligible.