It's Your Call
You know, I just went through getting an iPhone a few weeks ago. Went to the ATT store, got really frustrated by EDGE speeds, walked away from the purchase. Even groused mightily about it within another thread on this site.
A couple of days after I posted my rant, I received a gift from my wife: yup, she bought me an iPhone. Not out of love, but just because she was sick of hearing me talk about it. Her rationale: "just shut up and try it out for two weeks - you've got two weeks to take it back if you don't like it." My first thought was to immediately take it back - hey, 3G is coming out soon. Then I decided to use it for the two weeks - hey, I figured I had nothing to lose by trying it out.
It ain't going back to the store. I'm eating crow. Love this thing...don't know how I ever lived without it. My trusty travel laptop is now gathering dust. I just make sure I do my heavy-duty web stuff while I'm on Wi-Fi (which is about 75% of the time) and take what I get with EDGE. The whole EDGE thing is still a limiter on the iPhone, but it's not nearly as big a deal as I thought it would be...although I'd probably feel much differently if I lived in or frequently traveled to a country where EDGE is unavailable (and by the way, that would be darn near anywhere in the world outside the US).
After a few weeks with the iPhone, my advice: if you really need or want the iPhone now, and you accept the potential downside to buying now, go ahead and get it now. The iPhone you own won't run any worse when the 3G model comes out. Nor do I think that Apple will let the upcoming software updates turn all those non-3G iPhones in the field into near-bricks. So far as the lower price, that's the nature of new technology: the price always falls over time as new iterations come out, until the technology becomes a commodity. You can always make a case for waiting a little longer to get a better deal.
Wait if you can. If you can't, for whatever reason, buy it now and enjoy it. It's your call - just make the decision and follow through on it. Don't think you'll be sorry either way.
So far as accessories go, I bought an IDO car charger, an InCase cover with wrist and arm straps, and some very nifty Crystal Film screen covers from Power Support. I also picked up an Apple Bluetooth headset, but that might have been a waste of my money...just not using it much.