I am not thoroughly versed in all of the fine points but it looks OK according to what I know.
Shawnette would be someone I would go to for an opinion if I could.
That Amazon ad mentions two listed as used that caught my attention. The $53 dollar one with free shipping from Amazon Fulfillment would be the one I would get even with the blemishes it mentions.
But I just checked over at Devardi and they have an oxygen regulator for $33. It comes with a one year warranty.
The nice things about regulators is they are either going to work or they are not going to work so getting an inexpensive one that is cleared for sale in the US is as good as spending twice as much for the higher priced models.
http://www.devardiglass.com/Torches.htm.
The glass may be somewhat shocky but the hardware they sell is just fine.