For the scale I use those 2 during my pizza and bread classes.http://www.amazon.com/gp/product/B003E7AZQA/?tag=pmak-20
Used to measure flour, water and such. Very accurate and won't turn off on you at the crucial moment. Very good price.http://www.amazon.com/gp/product/B000P1NYE8/?tag=pmak-20
This one I use for salt, yeast and starter. Great on small quantities and very accurate.
Bought a Kitchen Aid 8 quarts reconditioned for $500 I think, about 2 years ago. Great for small volumes.
Webstaurantstore.com is pretty good but they are many others. Just double check the dough hook is included.
If you are looking for bigger letting me know as I am coming up with a line of commercial mixers.