They are good speakers, for in-wall or in-ceiling installations. All in-wall and in-ceiling speakers sell for a premium new.
Why didn't you google "MB Quart 90 M"? First hit I get is QL-90M (the actual model #) and identified as in-wall in-ceiling 8" woofer 1" tweeter, current in 1991 catalog.
Second search "QL-90M" gives me a worthless link to a valuation site that wants you to pay to play. So I then search "MB Quart In-wall In-ceiling" and get little. Off to eBay ...
"MB Quart QL" gets me quite a few links to sellers, the least expensive in-wall unit was $200 and looked decidedly cheaper than yours, the next least expensive hit was $275.
I stopped there, but all of that took about 6 minutes of my time. If they were mine, I would have spent more time (searching Kijiji, Canuck/US/UK Audiomart, etc).
Or just going by the appearance, brand, apparent quality, etc I would have put them up for about $40/pr and waited to see who bites.
I wouldn't feel too bad, I've acquired better speakers for less (as in $5~10 to free). I either use them myself (my service bench is using some Energy Take5's, free) or give them away or sell for cost as part of systems to friends who need some decent music. I check used sites regularly looking for bargains, not just price-wise but they also have to have genuine HiFi genes.
You'd be amazed at what some people I know are using for well under $100.
