It is highly dependent, but if you're curious you can check a website like tcgplayer.com and enter your cards in to get an idea. You'd want to look at the market value, rather than high/mid/low.

Also consider that if you did want to sell, selling to a store drastically cuts value. Individual sales aren't without their share of problems either.

I'm heavily involved in MTG, so if you did have further questions feel free to reach out.