if you want something inexpensive, but ver ystable, i got one at ikea for like $20 or less. it takes the paper roll, i would imagine as long as its the same width, it would take others. it only has one tray though so its not for storage, but for the price, and for the height, it was great. and if you need something that stores well, anything with storage is going to take up a bunch of room. its taller than the crayola easel, so my daughter who is almost 6 still has plenty of room left before it would be too short. chalk on one, whiteboard on the other. its wood, so its nice since its not babyish, like the plastic ones, so it will last the child, and it looks better than my plastic one in my kitchen.
it would be great to get that, then get one of those art kits with all the items, like chalk, pencils, crayons, paint, oil pastels. you open it up and all the stuff is on each side. they have some really elaborate ones, but they are great for storage, and they could still use them at the table when coloring.
if storage is a concern, i think the two pieces would be perfect for you. it really folds thinner than any other i have seen. there is nothing really to put together. you could also get a stick on thing, and add a clip to the one side that doesnt use the paper roll, so you can clip on smaller papers and paint them.