I had some bad experiences with AmScope.
(1) I order a microscope base and it came damaged on the mail, bad packaging, so I had to return the unit.
Then I decided to upgrade my microscope and purchased a new one from them.
(2) You have to check the prices on different items, they can have very similar units for about the same price, for example I was going to buy a 7x-45x microscope, but then I saw a 3x-90x with a couple of lens for a couple of dollars difference.
The microscope head came with some marks and the post with signs of oxidation. So check the unit when you receive in a good light condition room
There is no way to say what microscope model you receive, I contacted AmScope to ask how can I check that the microscope I order was the correct I have received, their answer is that there is no way.
The microscope is good so far, buy a cheap ~$30.00 White LED ring from Ebay if you can, at work we have halogen lights and they suck.
Regarding the barlow lens, I will say to try without first and then if you need buy a $20.00 from Ebay, I bought a 0.75x barlow lens from China and have not have any problems whatsoever.
David DLC