A quick search seems to show this was made in 1997 by a company called Authentic Images. Seems it part of a series. It looks like there was a standard production of this card and others, which seem to have asking prices around £30ish, the one you have looks to be a little different - the size of the gold card appears larger and the layout of the wording on the certificate is different and obviously limited edition run.
A broader eBay search shows different cards with quite a variety of prices, again mostly US based asking prices, which means it may be hard to set a price.
Not sure that is much help, but a start maybe?