I've never used the Cintiq 13 but have used a Huion type screen, which I ended up returning and purchased an ipad pro. The biggest reason was I use my computer for many things and hooking up the screen and unhooking it and making room on the desktop was too much of a hassle. The other drawback with the Huion type screen was the amount of space available for drawing. Even with a 22+ inch screen a LOT of it was taken up with pallets.
I returned the screen and purchased an ipad pro 12.9 and have not second guessed my decision. The screen size, power and portability make it worth it.
There is a learning curve and it is not like drawing on paper.
If money s tighter you can do a couple things - either purchase a refurb from apple (full warranty) or purchase with their 18 month 0% interest offer.