We've used tablets for the last 8 years at work.. the Viewsonic I pointed him to, was a "slate tablet without a keyboard," manufactured almost 10 years ago now. Unlike the IPAD, it had firewire, vga, touch screen, and could run things called PROGRAMS... like I dunno.... Office.
I like the iPad, but like everything Apple, it isn't new, or innovative, it is just "pretty." By "pretty" I mean generally needlessly expensive.
With your critieria... you eliminate the ipad, unless you want to do bluetooth for your keyboard and mouse.
You are likely better off with a Netbook.. in that price range... just saying. 10 inch is all I remember seeing in a netbook (I don't think they made a 12 in any brand).
the no fan or moving parts? Hmmm. So you want a netbook with a solid state hard drive then... I think the criteria are too high for that price range new I bet, unless you are talking used. Have you tried
Geeks.com - Computer parts, Laptop computers, Desktop computers, Computer hardware and looked for one?
PS: blast me all you want, I own an iphone4, replaced my droid2 with it. Have to say I miss my Droid.. but the iphone is better built.