jnanian,
You can get mirrors re-coated
here.
I just checked their link and they may have website trouble at the moment..
Here's their contact info:
Vacuum Coatings Ltd (Scientific Mirrors)
66 Barrett Road
Walthamstow
London E17 9ET
Telephone / Fax 020 8520 5353
enquiries@scientificmirrors.co.uk
There are places in the US that I looked up a while back but I used the English guys as they were closer to me.
I actually got a mirror for my Pilot 6 recoated by these guys. They did a good job, albeit a bit slow, and it came to around 12 pounds, I think.
Unfortunately, I broke it in half while reinstalling it! My first ever glass breakage. Oops.
The mirrors from compact cases are very good. Some of them have paint on the back that will not come off with acetone or paint-stripper - Chanel is one brand to avoid for this job.
I spent a lot of time trying to cut the ~1mm glass but didnt do too well. I think the best thing to cut thin glass is a Dremel with a cutting wheel (which I don't have).
In the end, I ordered 'dolls house' mirror from a seller on ebay. It's 1mm thick plastic with a mirror surface and it works perfectly (also, you can cut it with a knife or scissors!)
Ground glass is easy if you can get the thickness of glass that you want - small picture frames often have quite thin glass ~1mm also.
Get some valve-grinding compound from an engineering supplier or walk down the road to your nearest motorbike mechanic and see if he'll give you a blob of it

If you do a google search, you'll find a description of the process (fairly easy).
I have also used wet&dry sandpaper after the grinding paste, to get a finer grain on the glass. I use it to sand cracks or chips off vintage glassware, starting with about 400 grade, and 1200 will almost give you an unnoticeable finish.
One other thing - I bought some A4 fresnel lenses for a few bucks each and cut the center out to place under the ground glass in my Pilot 6 (which is known for it's dim finder at f6.3) and it brightened up quite a bit.
There's always a trade-off with DIY vs BIY
