Local game stores buy cards at a discount and sell them at market value to make a profit, so you will get less in return compared to other options
Sylvan Tutor Sylvan Tutor is a 1-mana sorcery that tutors any creature straight to the top of your library
You can drop this on turn three, sacrifice a two-drop artifact dork for two cards and two mills, sac it to Goblin Welder to swap for something you just milled or what you sacrificed, and then swap the sacrificed or milled card on turn four for this to keep
The risk with general marketplaces is always counterfeit products stick to sellers with extensive positive histories and avoid listings priced significantly below market value
These decks are all a bit underwhelming, but that is for a good reason as they make it super simplistic and cheap to start playing
Even worse than Time Spiral, the Jar required no activation cost once it was on the table