found a gameboy for $20 worth it

Based on the catalog data, the value of a Game Boy can vary drastically depending on the specific game or model. For a general Game Boy, the sold comps show values ranging from $1,355 used for some titles to over $4,381 used for others [1].

Since you found one for $20, the market verdict suggests this is a BUY [2]. The estimated net profit after fees would be around $3,795.78, showing a massive return on investment. Keep in mind that the catalog prices are for specific, often rare, games, so the $20 price point is likely for a very common or loose unit. You can check the live eBay listings shown on the page to compare current asking prices against these sold values.