I was in a similar situation recently and ended up going with an internet tablet--the Nokia N800, specifically.

Yes, it's Linux-based, so you would need to consider whether you're ready to deal with that when it's called for. However, it's very compact and meets all of the functional requirements you mentioned except for a wired keyboard (it supports bluetooth).

The N800's o/s has improved significantly since its initial release; its GUI offers straightforward access to the browser, Skype client, IM client, & other tools. Its wifi functionality is strong, as is the ability to tether to Bluetooth-capable phones. The street price ($350) is far friendlier to the pricepoint you cited. (What's more, it's not an Apple product! )

Certainly worth considering.