You've got tons of choices for well under your price range for an integrated stereo amp or A/V receiver, with lots of good suggestions already so I'll leave that alone. But instead of connecting your iPod I recommend a network music player such as the Slim Devices Squeezebox or the Roku SoundBridge. The advantage of which is it gives you instant access to all of the music on your computer, and is not limited by file format. Note that neither of these can play DRM music from the iTunes store (although the Roku can play Play-For-Sure downloads).

The advantage of the Squeezebox is it runs on 802.11G vs. 802.11B for the Roku and has slightly better sound quality (with its analog outputs, anyway).

The Roku is half the price and works with iTunes out of the box - no software to install, plus plays Apple Lossless natively (the Squeezebox has to transcode Apple Lossless to .wav). Also the Roku can work with virtually any server software (I use Firefly Media Server myself, which is free and can play more file types than iTunes, plus Windows Media Connect 2 and iTunes on occasion) while the Squeezebox only works with SlimServer.

If you can run an ethernet cable the wi-fi B vs. G isn't an issue. If not and you need G speed you can pick up a 802.11G bridge for less than $50 if you shop around (the internet) and plug that into the Roku's ethernet port.