I have been trying to find a large, deep welled palette for ages but was also concerned about the wastage from unused paint going dry (acrylic).
Whilst in my local "The Range" I spotted a couple of items and had a bit of a brainwave.
A flat case and separate tray with individual wells.
I filled all of the wells with paint and placed a piece of greaseproof paper on top, and on top of this I place a wet paper towel to keep moisture in the case when the lid was on. Its been a week so far and the paints haven't dried out. Have a look in my gallery "Stay wet palette" for pics. the case and tray came to about £6!