We groom Suzie ourselves, and we use a cheap clipper from petsmart that is crap. I'm gonna start to try to save up some money and get my mom to help pay to get a nice one that will work all the time, not when it wants to. Now my question is, what size blade would you use to do a personality clip on a Shih Tzu? If you do not know what a personality clip is here is a link to what it is.
I groom my Lhasa Apso usually, and will most likely groom my Shih Tzu as well (he's 11 weeks old so doesn't need it yet). I bought the cheap pair "made for pets" from Target or something. They sucked. They worked the first couple times, but then just got choppy...JUST when I started knowing what I was doing. Then I bought a pair for human hair from Sally Beauty Supply. They work so much better. I paid about $40 or $50 for them. They cut evenly and don't pull his hair. The only set that works better is my friends professional grooming clippers, but hair grows back! So, the set at Sally's would be my suggestion.
As far as blade sizes, I have no clue. The Sally's set came with several different attachments. One of them always works, depending on how I want Merphy cut. Good luck!
Even if you are on the right track, you will still get run over if you just sit there. (Will Rogers)
I get my blades on ebay actually. Usually get a better deal. However Petedge.com would probably be my favorite for supplies. If you get the clipper there they will send you a free 10 or 7F blade, which is really short, but the 10 can be used on the sanitary area and the 7F if there is matting.