I bought a DVD from:
http://www.yorkietalk.com/forums/yor...oming-dvd.html
In the DVD, Sue gives you some great recommendations for all of the grooming equipment you will need, including clippers, blades, scissors, etc. I believe she recommends the Oster Golden A5 clipper (Petedge). Also, the No.10 blade is the one most often used with yorkies.
I bought the Oster Powermax, which is fine for the grooming I do - if I were a professional I would have probably chose the Golden A5. There isn't much difference though between the two styles of clippers.
The DVD is worth the $$, if she is still offering them, I would recommend getting one.