When buying from Amazon, be sure to look at who is the seller as this can affect returns.
If the seller is Amazon ("ships from and sold by Amazon.com"), it is easy to return to Amazon within their return period (which is usually 30 days). Of course, the item must be in good condition and in original packaging. If there is something wrong with the product, return shipping is free. If you have just changed your mind, you pay the return shipping. I have returned defective items and asked for a replacement, and Amazon has always sent out the replacement immediately, before they even receive the item I am returning. I have also returned defective items for full refund. A few times I have paid the shipping to return an item about which I had changed my mind.
If the seller is someone other than Amazon ("sold by so-and-so company, fulfilled by Amazon.com), the seller is a third-party seller and different return policies apply. You can probably Google "Amazon third-party return policy" to find the page that explains those rules. In general, I think Amazon requires third-party sellers to take returns of defective items; however, for changes of mind the seller may not be required to take the return. Also, there may be shipping charges involved on the return.
I mentioned the above because you mention getting burned on a Singer from Amazon. If the seller is Amazon.com, really all you need to do is thoroughly test out the item before the 30 days is up. If there is something wrong, scroll through your "orders" until you come to it and click on the return button. Once you give a reason, you can print out the return postage.
Looking at the current Juki TL-2010Q listings, I see they are all third-party sellers. Two of the sellers are very well known and have good reps on the internet, so I wouldn't hesitate to purchase from them: SewVacDirect and SewingMachinesPlus. The other one is precisionsewingmachines, which I have not run across before, and if you look closely at their listings they say "ships from and sold by precisionsewingmachines". This means that you are not really dealing with Amazon at all; they are just advertising their product on Amazon. Whenever purchasing from a third-party seller, it's a good idea to click on their name in the listing to see customer reviews of the company. Don't rely solely on the percentage of the review; click through and read the reviews to see what exactly the negative comments are. Sometimes customers give poor reviews when the issue was out of the hands of the seller.
Hope this isn't too far off-topic. I got carried away........