So can any of you who voted against the posting answer the quote above about the widowed lady?
I had a really long reply that I'd just finished up and decided to delete... I think it all boils down to this, anyway:
Most people would not find it entirely acceptable to take advantage of the little old lady's ignorance. The solution would be to advise her that she would be able to get more for the T2 machine. If she still wanted to sell it to you for $50 knowing that, it would be fine to buy it. Some people (myself included) are concerned only with getting a price they can be happy with for items they sell, especially when they're being put into the hands of someone who can use them. Not everyone is concerned with dicking someone out of every penny possible, to the exclusion of all else.
Posting auctions here in order to "help the ignorant" is not the equivalent of informing the little old lady. To make the analogy accurate, you'd have to go home and start taking out ads on the little old lady's behalf with a listed price of $350 (or whatever is standard) for the machine. If you see something listed on eBay that you feel is in error, and want to "help the seller", drop them a line and let them know what you believe the error to be. If it truly was an error, and they really want to, they can correct it. If not, then don't go out of your way to make sure no one gets "a deal" out of it.
My question is this: why is it okay to harm the buyer to the benefit of the seller (as you're doing when you negate the work they've done to hunt down an item and save money), when the opposite is clearly not acceptable?