I dont have a smartphone at this point but I still have a bit to say hahah.

I am using an Ipod Touch sometimes at home now to get away from the computer chair, and its ok for browsing and that includes Sharetrader, but of course it doesnt have 3G so you need a wifi zone if out and about.

From what I know the Samsung Galaxy S2 is a premium phone comparable in quality with the Iphone. Both will set you back well over a grand. But increasingly there are smartphones available at much lower prices that will do those straight forward email and web browsing tasks, as well as have cameras and music
.
EG have a look here at the ones in the $0-500 section
http://store.telecom.co.nz/mobile/prepaid/compare
Attachment 3852
for example the HTC Wildfire at $399
I am pretty sure if you checked it out you would find this would be a very functional smartphone

Even cheaper at $179 the Huawei X1 does nearly everything the HTC one does, still has a touch screen and a browser and email.
If you're going really budget it may pay to get the saleman to confirm it does what you think it will.
Make a list of what it is you want. eg camera. radio mp3 , document viewer and choose to fit that

Of course Iphones are nice....
I've used one and an Ipad2 and they are easy and fun. Just really expensive.