Building a budget gaming system with son so he has a desktop to play his Steam games. Leaning towards a 250 GB SSD for OS and his most used games, then a 500 GB HDD for the "over flow" games and other data. Does this sound optimal since I already have the 500 GB HDD (WD Black) and really can't afford more than a 250 GB SSD (again, budget build). Is their a more optimal use of the 500 GB drive? All of this is really new to me so hope I phrased my question appropriately.
Sure that would work great and you can install the STEAM installation with the game folder on a different drive so you don't have to download them again -- just read over THIS and you will see the changes in the OS drive that you need to make to use the games off the HDD.
And you honestly don't need to have any of the steam games on the SSD or a bigger SSD, once the games load they run the same from an SSD or HDD. And if it is budget and mainly for gaming, I would consider a smaller SSD (120/128GB) and spend the extra on the video card or if you already have one just save the money.