What's "not really"? Not really a good deal or not really a warranty? A warranty is a warranty, whether its 30 days or 5 years. Caveat emptor...
If you see a better one, post it, that's the point of this forum. If you don't think this is a good deal, look elsewhere. I wrote they "typically will offer a 30-90 day warranty on most of their receivers if they're refurbished", this a fact. In addition to this, all Onkyo receivers they sell have a one year warranty direct from Onkyo. I've been following and using uBid for the past 5 years, so I'm pretty familiar w/most of their workings.
I didn't mention shipping charges 'cause I ain't your momma, I would expect any educated consumer to read the fine print anytime they make a substantial purchase. If they offered free shipping, I would've noted it as I have in several other postings.
In regards to an extended warranty, do you mean something like
uBid's Extended Protection? As far as extended warranty service from a third party company, I have only had to experience this once w/a computer and it wasn't pretty. Manufacturer warranties are your best warranty solution, but as I said earlier, with risk, there is usually reward.
I myself have not had (nor have I heard from others) worse experience with refurbished products than I have with purchasing new. If you can find something better somewhere else, feel free to share, that was my intent with this thread...

-TD