If you don't live near a true electronics store like A1 in Toronto, when RS stopped selling electronics parts over 15 years ago, the only recourse one had to buy small items: solder, wire, etc., was a hardware store, and for components for repair like pot knobs, pots, electrolytics, resistors, etc., was mail order. Because of the minimum charge made by most electronics shops, usually $10-30, and shipping of $10, you're paying 30%-100% in shipping cost and so to leverage that you need to buy a lot of parts and keep the inventory of parts for yourself in your lab. The cost of shipping is far more than the higher retail prices of RS and the local taxes, for small purchases.
In my last trip to RS some months ago, I bought solid AWG wire for $4 for 3 rolls, and a set of Extech probe accessories: mini clip, alligators, etc., for $20 which was sold by Amazon for $15, with free shipping if you exceed $25.