Twenty odd years ago I was using a stay wet pallet all the time but I was also using for the most part artist acrylics rather than hobby paints. It was just a nice flat Tupperware box but it worked well for me. I had another go with the idea a year or so again but a lot less successful, mostly because I was using a tub that was both high sided and was not flat enough at the bottom.
So I have had another go this week using an old sandwich box (size of a slice of bread) and it works much better. It's great to come back to paint from a day or two before and still be able to use it.
I still use Windsor and Newton sheets as the thick blotter paper holds the water and the tracing paper type sheet holds the water away from the paint but keeps it moist.
You just need to make sure you hit the balance between to dry and too wet, a bit of practice sorts that out for you. No need to spend £15-30 on a proper set up as this works well and besides I don't have the room for the real deal.
In the background is the British Naps I am working on at the moment and some of my son's work awaiting varnish but also two Vikings I am working on as well.