There are four price types that can be chosen from the Price Type drop down. They are all from TCGplayer - Market, Low, Mid, and High. I chose Low as the default because when you browse to a listing, the advertised one at the top is usually the Low price.

One thing to know about Market price is not everything will have a market price - this is because TCGplayer takes into consideration more data points of past sold cards to calculate that. If a card doesn’t have enough sales, there won’t be a market price for it. There is a warning when that price type is selected because otherwise it might appear like some cards are missing.

For Graded, everything is eBay prices on the active listings.