Thank you all who responded! We've found exactly what we need!
A couple of months ago, the president of our local astronomical society put me in touch with a 13-year-old who is interested in building a telescope. He has a 6" f/6 equatorial mounted reflector now that he uses quite a bit. Last week he taught himself to use setting circles and logged 15 M objects - what 13-year-old does that? The kid is sincerely into astronomy.
He is convinced that he wants a dobsonian of at least 10" aperature. I explained to him that he could likely buy a very nice 10" for about the same as he could make one, without the labor. Nope. He wants to build. He has a pretty good idea about what he wants - the kid has read Kriege and Berry... He has put together a nice little war chest for the project, and he has his parents' support.
So, before he goes off and orders a $350 commercial mirror or a $100 focuser, I told him I would see what Astromart could do on his behalf.... so with that in mind...
We're looking for a 10" newtonian primary, pyrex preferred, f/4.5 to f/6.5, but f/5.5-6.0 is what he thinks he would like best. Diffraction limited or better. Usable coating preferred, but pristine is not a requirement.
Other parts that he'll need (i.e. I would rather not fabricate or see him spend a fortune on) are:
Secondary Mirror and holder.
Spider for 12" ID.
I have teflon, kydex, ebony star, and baltic birch, and am willing to help him build it, so if you can help out, let me know what you have and at what price, and I'll talk to him at our club's meeting on Friday. I'd like to see him have a nice scope without spending a fortune.