Hi Bern, years ago a hand finished parabolic mirror was the only way to go.
You could purchase a machine finished spherical mirror that was of good quality. Still to this day a very high spec mirror is only going to come from a skilled polisher. You can pay many more times the price of a modern cheap mirror. (ie: Zambuto, Galaxy,Suching etc).
These days I have seen some very nice mass produced mirrors from Skywatcher,GSO and Orion. I think the Chinese have perfected machine figuring to some degree. The beauty of this is it makes it an affordable hobby to get into.
Here is a test report of 2 GSO 16" mirrors (quite good for the price).
http://translate.googleusercontent.c...9-bQ#post35463
Here is a test report from a fine hand made mirror
http://translate.googleusercontent.c...hb_g#post35325