I’ve bought lots of astronomy related stuff from Amazon. Just a month ago I bought a 12” Sky-Watcher Flextube SynScan with GOTO Dob for $2300 which was $500 cheaper than most of the traditional astronomy vendors were selling it, although I did see after I had ordered it that Adorama had it for the same price. I’m a Prime member so always get free shipping and usually it’s delivered in one to two days, even the same day on small orders over $25. I also charge all my purchases to my Amazon credit card and get an additional 5% off and pay the card off every month so there is no interest charges.
Never had any problem with returns, they email you a return shipping label and you just take it to your local UPS and they box it and ship it back to Amazon for free. In fact, when I bought the Sky Watcher there was a problem with the hand controller and I emailed Sky-Watcher via my Amazon account. Someone from Sky-Watcher in CA called me within a couple of hours, went through the issue with me and I ended up returning it and they sent me another one in a couple of days.
The trick is just to buy items that are sold and shipped by Amazon but are supplied by the original manufacturer (Sky-Watcher, Celestron, etc). I have also bought from many of the traditional vendors directly (Highpoint Scientific, Astronomics, Agena etc.) as well and have also had some problems and returns, so nothing is guaranteed regardless of who you buy from.
I made my first purchase yesterday from Adorama and it was shipped the same day and I got free 2 day air shipping and it’s scheduled to be delivered tomorrow (Televue Delite 5 mm eyepiece). I thought that was pretty impressive and their prices are usually competitive. I usually buy based on price and the quality of the vendor.
Good luck with your purchase.