There are other companies that copy the Microsoft Surface and many of them look pretty good. Your problem is that you won't be able to buy one of the new ones for $500. You will have to either throw more money at it or buy used. If you look you will be able to find what you want either in your price range or pretty close in a used Surface 3 pro. My recommendation, don't consider any Win-10 laptop under 128MB.
I haven’t made the break into a tablet yet. I would probably just buy an elcheapo to try it it out.