First thing to do is to educate yourself so you do NOT get taken. Read some books or at the very least do a Google search and visit some web sites.
The "curved grip" as you call it is called a Type C stock. This will command a little more price wise than a straight stock, but a Type C is easier to shoot.
First thing is, do you want a shooter or a collector? Do you know what a high number is? Did you know that there are some 1903's (not to be confused with a 1903A3) that are unsafe to shoot?
My first bit of advice would be to visit the CMP web site. They are currently selling 1903's and you can also get a little more info. there as well.
www.odcmp.comThe key to not getting ripped off and getting what you do want is to know what you are doing. There are many out there that will tell you what you want to hear, and not necessarily the truth.