New ipod touch 5th Generation or Used iphone 4s?

I currently have a 2nd generation ipod touch. I was looking to upgrade my touch to the newly revealed ipod touch 5th generation but the technical specifications have got me thinking. Would it be smarter to buy a used iphone 4s and use it as an ipod? Or even with a prepaid card for calling using the rest of the functions over Wi-Fi. Jailbreaking and unlocking would not be an issue for me.

So basically, Is there a large difference in the screen resolution in both (forgoing the size)?
Is the 4s's 8mp camera better than the new technology in the touch's 5mp camera?
And what would be a reasonable price i would expect to pay for a used 32gb iphone 4s?

Is this really in question?
the iPod touch 5 and the iPhone 4S have the same processor, they both have siri.
The iPod touch has a 5 MP camera with the same technology as the 8MP in the iPhone 4s.
The iPod touch has a 4" retina display and the iPhone 4s has a 3.5" retina display.
Its up to you what you want, id go for the iPhone. I don't know your location but here where i'm (toronto, canada) i've seen some local ads for the iPhone 4s 32 gb ranging anywhere from 400$ to 450$

Get a gym membership instead!