I actually almost set something like this up out of college (too bad i had to get a 'real' job...) I was hiring my younger brother and his friends to go to tag sales, buy items from people for pennies, and then i'd resell them on ebay. I'd give them a cut of the profits that scaled up with the final price - even though i bankrolled them- this way I gave them an incentive to find high quality items.
It worked pretty well- except when they went back to school.
What do you want to know? There are a lot of these types of small shops now so there will be competition... I would just do a google search and take a look at what you see. I would suggest she become certified in appraising items - I'm sure there are classes in the city she could take. Maybe specialize in a certain kind of item to set yourself apart?
You will accumulate a TON of junk too- so unless you are willing to rent a large storage space, make sure you have a large room that you can set aside for it.
It actually gets time consuming to list items on ebay- by the time you take the pics, add them to your layout, and write up somethign nice about them, you will be surprised at the time you spend! I would focus on high end items or things you can sell for more- unless you are going to hire some local kids to do writeups for you listing that $2 item that will sell for $3 will end up costing you money.
Also factor in shipping costs- not the actual shipping itself, but the boxes, tape, packing material, etc. that you have to buy. You can save money on boxes by going to the local USPS and taking some from them.
An alternative is if she becomes a real appraiser she could go out to clients w/ high end items- photograph them on site, and then list them for the client on ebay. You would take a % of the final price.
You could also do real dropshipping on ebay- find a company willing to dropship items for you. You sell them on ebay, pay the company the wholesale price for them, and the company will ship the items to the customer direct. Your only risk is the cost of listing items if they don't sell.
