The 1/8 "wave surface accuracy" is really 1/4 wave peak-valley accuracy, which is a better indicator of how the mirrror will perform. In my opinion, a 1/4 p-v wave optic just passes for an acceptable telescope mirror.

I have never bought Orion optics, but making your own 8" mirror is not too difficult and you if have the patience, you could make it much better than 1/4 wave p-v.

The ATM links page on my website:

http://my.treeway.com/observatory1/

provides links to telescope making books, telescope supplies, and information on mirror and telescope making. This ATM links page is only the tip of the iceberg when it comes to the number of telescope related websites, so surf the net.

Lastly, here`s a site that offers software on how to calculate the size of the secondary mirror:

http://zebu.uoregon.edu/~mbartels/programs/programs.html.

Good Luck