I want to trade my wifi for a 3g
I don't mean to discourage you from your decision but are you just trading it because you think 3G is more convenient or just getting caught up with all the 3G hyped? I was once in your position and as the day goes by I'm just fine with wifi and uses my iPhone to tether with on a minimal occasion. Determine your usage with your current iPad wifi and see if you really need the 3G and then decide from there. Just trying to help out a fellow iPad user. Best of luck.
I was in the same position. I got a Wifi on launch day, and planned to trade it + some cash for the 3G model when it came out. However, the more I use it (and tether using Joikuspot on my Nokia phone), I think the advantages of the Wifi unit (longer battery life since your not running HSDPA radios and no "3G" restriction since my 3G connection is over wifi) were enough to sway me to keep mine.
I figure, I don't have any of the reported defects some 3G units are seeing (light leaking through the case), and since I already have 3G wherever (with much better signal/speed since it's using a Nokia antenna) that for me I can't see spending 25 bucks more a month for separate data access.
Not knocking the 3G Ipad at all, but for me, I think I'm sticking with my wifi unit after all.