Best Price for iPhone 4-Holidays

Me and my fiancee both have an iPhone 3G 16GB. I see them going for in many cases over $200 on ebay so I hope to sell both of ours there.
We want to upgrade to the iPhone 4 and likely will get the 32GB version.
With the holidays I am wondering if anyone knows of any good places to buy them. I know Apple will have a Friday sale but with it selling well I don't know how motivated they are for sales.
I have seen that AT&T offers refurbished which we'd be happy with. As well, I'm interested in other places like Amazon that may sell them since I can buy them tax free. I may be able to get it cheaper than buying refurbished from AT&T.
Either way I am wondering if anyone knows of good places I can get them refurbished, tax free, or any other sales. Thanks.

There aren't a whole lot refurbished right now because they are still fairly new. And a lot of the refurbished ones are used by apple themselves.

When did you get the 3G? You do know you can upgrade every year right? Even if you have a two year contract. Most people apply for the annual upgrade with signing a new two year contract. That would mean it would be 200 for the 16gb and 300 for the 32Gb. Right now I just don't see you getting a better deal than that anywhere and if you did it wouldn't be for much more cheaper. But I don't see it happening.

I'd just go for the brand new one. If you plan on staying with AT&T you shouldn't have any issue signing a new 2 year contract anyway. Most people don't realize this and think they have to wait for the "new every 2" and it even shows in their account that they aren't eligible for upgrade until the 2 years is up online. But most plans qualify for annual upgrade. Just go into a store or call and tell them you have had it over a year and want your annual upgrade.

I didn't realize I can get an annual upgrade. That's good to know for the future. Now I have the unlimited data which I know is no longer available. If I get a new contract, do I still get unlimited data or do I switch to the 2GB limit?

If you have the unlimited data right now you should be able to keep it. If for some reason you get switched to the 2GB data plan, call AT&T immediately. they should have no problem putting you back on the unlimited plan, because your account history will show you did have it.