An OK buy. Pretty much any working console is a buy for $20, with the box is a plus.
This is great for testing games before you sell them, if nothing else. This will also play PS1 games, some of which are hard to find in playable condition and worth testing.
Most PS2 games are a dime a dozen at this point. Unfortunately, I don't see any best sellers or rare titles in those games. Most sports games are near worthless unless they're less than 3 years old.
Also, games are much harder to sell without artwork/cases. They're still sellable "disc only" if they're popular or rare titles.