Well, this an interesting question as I have read quite a bit about discount software houses of this type- with most of the articles warning people away from them. There is a reason that the price is consistently roughly $1800 at well known reputable merchants such as you noticed at Amazon. Other major merchants have it for roughly the same price- places like Mac Connection, Mac Zone, Mac Mall etc. and retail establishments like Staples, etc. Do some more checking and you will see what I mean- and think of the old saying that if something seems too good to be true, it probably is.
I checked out all three of these sites online, and on a site called resellerratings.com which I refer to alot. On resellerratings the one that had the most reports on it was softwaresurplus.com in which all 7 ratings were "very dissatisfied". You can see that at
http://www.resellerratings.com/store/Software_Surplus
estockware.com had no ratings yet, and saveintheusa.com had only two- and a rating of 5/10.
One thing I would be doing is checking with Adobe ahead to find out if any of these are authorized resellers of Adobe products and I doubt they will be. Keep in mind that no matter what these sites say the return policies are, once they have your money they can do what they want- and failure to live up to site promises is one of the most common complaints. If you do wind up trying to purchase here, make sure it is with a credit card to have any hope of having any leverage (but at the same time, giving a questionable site credit card info is a risk in itself as you will note in a couple of reading resources I will give you below including some fine print on some of the sites that by purchasing with a credit card you agree to give up your right to do a chargeback if you are not satisfied!

)
Anyhow, none of these sites have
all of the common tipoffs that they are fraudulent (such as noting that you cannot register your programs online, noting that the software is OEM, or that the software will be provided in non boxed sets, etc.) but all fail badly on one of the common tipoffs in most of the articles below- that being the vast difference in price between their prices and the prices for the products from reputable, authorized sellers.
Please be suspicious and take the time to carefully read the short articles below before sending that kind of money to them! It will be worth the time investment I am sure!
Simply put from MY perspective- there is no way I would try it.
Anyway, to read more about the phenomenon of cheap software sites check out:
http://www.hoax-slayer.com/cheap-software-spam.html
http://graphicssoft.about.com/cs/faq/a/softwarescams.htm
http://www.theregister.co.uk/2004/06/03/oem_software_scams/
http://ezinearticles.com/?Software-Scams---To-Cheap-To-Be-True?&id=279679