Okay, so if you want to use a touchscreen tablet for drawing, you basically have three options, though I don't know that any are within your budget. The biggest thing with a tablet for drawing is you need pressure sensitivity, which most tablets don't come with by default. So your options are...
1) iPad Pro with the Apple Pencil. The iPad pro itself is about $1000 USD, and the Pencil is sold separately. You can't currently run Krita on an iPad, but there are a lot of great drawing programs you can use, including Procreate and Clip Studio.
2) Microsoft Surface computer, which is a hybrid laptop/tablet. These start at about $800 USD, and go up from there. For artwork you kind of don't want to get the cheaper base models, because you'll probably need the extra RAM and hard drive space to handle large image files. Because it's an actual computer, not just a tablet, you can run full versions of all your favorite art programs, including Krita and Photoshop.
3) Wacom MobileStudio Pro. It's sort of like a Cintiq, but a whole portable little computer. It runs Windows and functionally is considered a computer, so you can run full versions of your art programs, and has all the functionality of using a Cintiq. These run about $900 USD for the base model, and go up with bigger screen sizes and improved computer specs. This device is kind of clunky for actual portability, because you need to carry the tablet and the charger and the easel and probably an extension cord and an external hard drive. The battery doesn't last very long, so if you're going to use it for more than two hours or so, you need to plug it in.
As far as used technology goes, I would say as long as you get it Certified Refurbished through Best Buy or Microsoft or Apple, where it comes with some kind of guarantee and it's been through proper resetting and virus-checking procedures, you should be totally fine. I've bought Certified Refurbished gear from Best Buy several times in the past with no complaints.