My Nokia E90 is probably the best value for money Smartphone I've had. Its the second one, but I have used this model now for over 2 years and the functionality is still very compelling for a business user. Second beat value for money is my HTC Touch Pro 2 - like the E90 but better in some ways but the OS is not as reliable as Symbian.
I think my smartphone (a Touch Pro2) is a great value. Most ppl believe that netbooks are a great value. But my smartphone costs roughtly the same as a netbook. Since netbooks are so underpowered, you can't do more than web browsing and editing office documents. And my smartphone can do those things just fine. Plus it's more portable, can be used as a phone, portable music player, camera, and GPS device. Also, I can use it to browse the web and get push email outside of wifi coverage.
In April I bought new Treo 750 for about 100€ and for my wife new Treo 680 for the same price. It replaces our old PDAs + mobiles. We both are still happy ;)
Got my Nokia E71 for free with points. Of course I'm tied into another 18mnth contract, but that doesn't change anything in terms of what I would have to pay anyway.
I consider it to be a pretty good deal myself!
My HTC Hero is amazing value for money and a lot cheaper than other options.