The Onkyo 602 should run closer to $300, and will be fine for HT but if you are picky about music performance I'd look at Harman Audio on eBay for the best bang for your buck. Should be able to pick up an HK 330/335-430/435 in that price range with full original manufacturer's warranty.
And if you decide to go 2 channel I'd look at a NAD 320bee integrated amp for $300-400.
I agree with Edster. Although I would go to Harmon's site directly and buy. The prices there are a few dollars more than the strating bids on E-Bay, and a lot of the stuff has free shipping. You could save a few dollars on E-Bay, or you could end up paying more, depending on the way the bidding goes.
A better alternative than the H/K's would be the NAD C320BEE or C352, if you can live without a tuner. NAD has a seperate tuner for about $300 retail, but when adding them up it may be out of your budget.
Edster - Do you know that Harmon's website sells their refurbished stuff directly?
Ziggy...Maybe it depends on the model. The few I looked up were the stereo receivers, and there was about $10-20 difference between the Harmon price and starting price on E-Bay. I guess you have to look at each one individually...
Also Stu, unless something has changed recently (and I'll admit I haven't checked since I bought the 235), the starting bids on the Harman Ebay auctions are always $1. And you definitely need to know how much those pieces cost elsewhere - I saw a couple auctions for the 235 go over $350; most fell in the $280-300 range; and the $261 I won with was the lowest I saw in a couple weeks of watching/bidding.