Is $300 a fair price for this second-hand PC setup?

Before you decide, make sure to get more details about the setup. Check if it has a dedicated graphics card, the power supply unit, motherboard model, and if there's an operating system included. Also, find out how long it has been unused and when it was last cleaned. If it’s just the Ryzen 5 5600G, you might struggle with gaming unless you plan on doing less graphically intensive tasks. Just some things to keep in mind!

Looks like you got some more specs! That Ryzen 5 5600G is decent for casual gaming, especially if it was bought last December and is still under warranty. The 650w power supply seems robust too. Given that the parts are relatively new and still under warranty, $300 sounds like a solid deal to me. But definitely try to get a little room to negotiate just in case!

Thanks for the tips, everyone! I appreciate the feedback. I’ll make sure to ask about the condition and specifics before making a decision. I'll keep you updated!