When you find out how much the cost is for a ground blank vs. a regular flat one, remember that it`s going to take you about 3 hours of work to get that deep a curve ground into a blank (one of the mirrormaking group is working on a 10"F5 and it took him 4 1/2 hours with all the talking that goes on in the group to the point where we poured the tool). For more info on the method that is being used, go to www.access1.net/bobmay for my mirrormaking article or go to http://theastropages.com for the method. The work isn`t hard to do so don`t restrict yourself in the purchasing price based upon whom you can get the glass from.