I don't fundamentally disagree about the Pentas 3, perhaps $1600 is bit high. I've seen them go for less on ebay. Of course as Peter says condition is everything. The problem with getting this price is shipping. By the time these are properly packaged and shipped, you're looking at $2,000+.
On the BL3000s shipping is much less of an issue, but I'm not sure that $1200 is the right price. Again, condition is everything, but I've followed the prices on these for many years, and I've yet to see a pair on ebay go for that much (BV3000 of course are much less expensive/desireable). I may be wrong since I don't have a way to track 100% of ebay sales, but it's my sense. On the other hand, BL4000 would definitely get close to this price, but still perhaps not quite this much.
Unfortunately the second hand market in the USA is not as strong as in the UK. For example, I don't think a business like LyfeStyle AV would be viable over here. Still, B&O prices for second hand equipment are incredible when compared to most other brands of AV equipment.