If you want el cheapo DDS-es, contact Peter Walnes (https://secure.peterwalnes.com/), I got mine from him for peanuts. He has none listed on his webstore but you can e-mail him anyway, maybe he has some left. He is a great guy, I can recommend him. Fleabay has extortion prices on 'em, seen regular Fidelitys go for 50 quid a piece. But you might find an as-is one for next to nothing if you are willing to spend some time looking.