Sellers: When do you drop your price?

Bravo. Good for you. What you pay for something has no bearing on it's worth today. eBay has a great free option in left column 'Sold' and 'Completed Listings'. I don't sell much equipment but I do sell alot of vinyl. It's surprising sometimes. Some titles are worth next to nothing and some have appreciated nicely. It's econ class all over again.
1) Supply and demand
2) Condition, condition, condition
In real estate it's location, location, location but S & D is first then always C, C, C. Original to the item add ons (original packing box, owners manual, remote etc.) are always added factors. Personally, if those things are missing, I'll keep looking. They contribute to the condition of the item. Might be superfluous to others but it shows respect to the item as well as the buyer. Understand shipping boxes take room to store (my attic is full of them). All the above (well most) responses are good. Alas, I'm beating a dead (sold) horse. 

Something is worth by definition what someone is willing to pay at some point in time in some place by non urgent buyers. The more efficient the market, the quicker and more consistently the price will be very repeatable regardless of buyer and seller. I.e the stock market (assuming everyone has the same information).
Estate sales when being sold to the public “as is” “no minimums” are not efficient; there are urgent sellers. When real estate is sold with no contingency, the price is lower as the seller is motivated to move quickly.

Sounds like Hilde got a good deal when she bought and a market deal when she sold. Econ 101.

And would it be so awful if hilde saw a great deal and did in fact purchase to resell at a profit and the new owner feels they got a great piece at a great price...

As long as she was honest about the condition, age, how many owners, how long she had it, etc., who cares if she made money on it or thought she could make money on it when she originally bought it?

she’s filling a market need. And taking a risk. What if she couldn’t get what she thought she could? 

Agree agree. Not to get too detailed about it, but I'm a he. Last time I checked. ;-)