Is this possible without having to hire a 3rd party integrator and have a lot of custom and expensive software modifications made ???

The short answer is "probably not".

Also, you'd generally want to have someone reviewing orders before they were filled - certainly to make sure that pricing was accurate. A national retailer had a $400 piece of electronic equipment for sale off their web site for $40. They had sold over 500 of them in a couple of hours before the pricing problem was caught.

What accounting solution are you currently using?