I live in a rural area and I've found that if I can wait two days for Amazon to ship something for free (Prime), I'm going to save money versus driving 10-20 miles to go buy it, even at Walmart. Overall I'm happy with Amazon and Prime, with a couple of exceptions.
Several times I have paid four or eight bucks extra to have something overnighted, and Fedex is not up to the task. Amazon says they will refund the money automatically if they fail to deliver in one day, but I've never seen it. Unless I call to request a refund, I've never seen a refund.
Secondly, and here's a scam Mex should watch out for:
If an item is fairly specialized, you might see the primary listing from Amazon as, say "$41.99--out of stock". Then underneath you see that it's available from two sellers "from $41.99".
When you click on that link you go to the vendors listing where you find two entries. The first is the orinial listing from Amazon, "$41.99--out of stock". The second is from a tiny or new vendor , "$419.99--free shipping".
While I've had MUCH better results with the vendors on Amazon than I've had on eBay (I'm an eBay jinx--a digital "stuff" magnet), you still have to keep an eye on things with Amazon if you're shopping for specialty items mostly traded by small vendors.