Recently I purchased an Orbit manual water timer from my local Fleet store. I paid $6.48 for the unit at the store. I took it home and before I used it, I did a quick price check on Amazon to see if my local store was close to the Amazon price.

You might not believe this, but I found the exact same Orbit model number selling on Amazon for $149.00 and another place listed at $129.00! I showed Dear Wife the product listing and she could not believe it, either. I have no idea why online these units were selling for so much, but the next day I went back to my Fleet store and bought the remaining 2 units they had on the shelf. For less than $20 at my local Fleet store, I purchased about $450 worth of water timers listed on Amazon!
OK, the water timer was certainly worth $6.48, but I would never have paid more than $15 for a single timer. I don't have a clue as to why these timers were listed so high on Amazon.
Usually, my local Fleet store sells the items I want cheaper than what I can get off of Amazon, or eBay. But I always contributed that to the shipping cost of one heavy item compared to the local store getting lots of heavy items on one truck shipment. If my local stores don't carry an item, then I'll start looking on Amazon or eBay for the product. I have saved lots of money buy ordering repair parts for appliances from Amazon and eBay.
I also have saved money by ordering bulk packages of mower belts, filters, and spark plugs from Amazon. I got a bulk package of 3 mower tune up kit supplies for my riding mower from Amazon for less than it would have cost me for just 1 mower tune up kit locally. So, I will price compare stock items that I don't necessarily need tomorrow. Sometimes if you plan ahead, you can save money.