If you’re looking to go the DIY route (which is what I think a majority of this forum has information on), it depends on what exactly in in the 500 to 600 range. If you only have 500-600 for literally everything, including tools, parts, extra materials, etc., I echo what everyone else has said. It’s neigh impossible. If you already have a few things on hand (like a soldering iron, maybe a deck and trucks) you could probably pull something off for 500-600. If you have to buy literally everything, I don’t think you’ll have much luck in that range.
If you’re looking for already completed, reliable, and in that price range, I think it’s literally impossible. There’s some chinese boards that are completed and may fit in that range, but I’d question their reliability. If you want completed and reliable, I’d agree with @chaka, you’d need about $1500, triple your budget. A diy option offers the combination of (probably) reliable and (probably) in your price range, but it’s definitely not completed.
So basically, I think you can only really pick two of those three options: completed, reliable, and price point.