The new iPad doesn't necessarily make the iPad 3 obsolete
As a new owner of a used ipad 3, I can definitely say that what it is capable of doing will be more than sufficient for at least 2 years.
The ipad 4 may have the new chip and a better camera, but the 3 is for the most part the same thing. As I read in several reviews and comparisons, many people made the point that by the time their 3 is worn out or just getting on their nerves (don't know why it would lol), a newer ipad will be released, so upgrading to a 4 now is just pointless.
I say this even though I secretly want the 4 myself. I try as much as possible to profit from Craigslist by buying iPads on the cheap from people in need of quick cash, then taking my time and selling them for more..to the point I can upgrade at almost next to nothing.
For instance, I bought an ipad 2 last Sunday for $230...turned around and sold it for $315 on Friday. Used that $315 towards the 3 I'm typing on now that I got this past Sunday for $385 w/ all original extras, and a $50 value smart case.
I'm now trying to sell this for $425 and see if I get any bites. If so, I can nab a 4th gen for probably $425-450 with goodies, making my cycle complete.