I bought the Fisher Price one at TRU when it was on sale for Black Friday for my 21-month-old DD.
She loves it.
But, she also loves crayons. I bought her the thickest Crayola brand washable crayons that I could find at Target and a pad of "marker" paper. Don't bother with the triangle shaped ones, though. If your DS is gripping things with his fist, the triangle shape will make the wrappers slide off really easily when his hand gets warm on the wax. (We have this issue at my dad's house - he bought the triangle crayons for DD to use when she visits him.)
It took us some "on the paper"/"out of your mouth" instruction/supervision with DD to make sure she didn't eat the crayons, but now she'll happily color in her high chair for about an hour. She even flips the paper over if she's used up the available space on one side. (This is not typical for any child I have ever met. My DD is very ... different.)
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Liz
DD (3/2010)
"Make mistakes! Get messy!" - Miss Frizzle