I'm sorry I can't add much about the plate. Valuing German glass is difficult because the market is still forming. Peill from the 80s is generally less valuable than from the 60s/70s, but a limited edition item would still have some extra value. Ordinary larger Peill pieces like vases and plates vary in price (on ebay.de in Germany) between EUR 10 for the more common ones to around EUR 100 for the less common ones. Limited might have an extra premium, so my gut feeling is that you'd have to insure it for about EUR 200 max. That could change in future years, I think the market for quality German glass will get better in the future (someday when the financial crisis is over and done with).
And please, please, please can you help me as well? I'm a Peill & Putzler vase collector, and I have a lot of trouble finding catalogues (none so far). If your grandfather had one or more catalogues stashed with his collection, I would happy if we could talk about me acquiring them or a scan of them.
If you have 50 Peill pieces in boxes, I'm sure some of them are vases and I'd LOVE to know the pattern name and pattern numbers of the vases at some point to compare them with what I have. Also knowing the approximate time they were acquired would help me a great deal (some of them apparently in the '80s).
I have more than 30 Peill vases by now, but from most of them I have no clue which decades they were produced or what the pattern is called (but you can have a peek if you're interested via de link in my sig).
If you're inclined to help me out, could you email me (email is available in my profile)?
Astrid