Could you contrast your copy with this page: http://www.greatsite.com/facsimile-reproductions/kingjames-1611.html
(Claims most “1611” reprints aren’t.)
I'm reasonably certain that the text is identical to those in your ad. The text is the typical Gothic print of that day and includes the confusion that we of today experience with some of the characters, e.g., confusion between "f" and "s" for example.
I feel fairly certain that what I have is a genuine copy and I am a bit suspicious of their ad. They, of course, are interested in selling their product and the price, if that can be regarded as an indicator, would denote a high quality product. Just a suggestion. If you can print a couple of their pages, take them with you and compare it to the $5.00 version you might feel a bit more confident (or not). Good luck.