Can I buy an iPhone without a plan?

So I was thinking about getting an iPod, but I really like the iPhone a a lot more so I was wondering if there was any way I could buy an iPhone without having to pay for anything else. I want it to be like an iPod, no sim card or any type of carrier. Is there any way I could buy it and it would just work through regular Wi-Fi instead of 4g? I want it so that once I buy it I wouldn't be getting any letters in the mail or anything having to pay for the 4g or sim card and such. I want it just like the iPod where I buy the device and that's it.

You can buy your phone separately on somewhere like Ebay - get an unlocked one - and then choose your plan separately

Makes more sense, financially & otherwise to get an iPod touch to be an iPod, not an iPhone.