Hi Sam
Your CDC should stock all the Cambridge products and so I would ask her to get some for you, she can easily order with the rest of her stock and I'm sure her other customers would appreciate having the choice too.
If she's not willing, which is very naughty, then it may be worth looking around for another CD who is more accomodating - whatever you do please don't buy from eBay, you don't know what you're getting. (This is one of the reasons why CDCs should stock all products to avoid people buying from unscrupulous sellers on eBay)
HTH x