@ the question of the thread:
Any retina display iPad could be the right buy if you get it at the right price. If an iPad 3 in great condition with a battery that hasn't run through a ton of cycles ends up costing you $200, that's a good buy. But if you end up having to spend say $400 or so for a used iPad, or an older iPad, you might as well (in my opinion) shell out the cash for the newest version.
Definitely wait to see what comes out next.
One thing that I think is true: The iPad 2 and iPad 3 were both excellent buys (longevity-wise) for people who jumped on the bandwagon when they were released. The iPad 3 is proving to be the best bang-for-the-buck iPad currently, since the iPad 4 hasn't outshadowed the iPad 3 in the same way the 3 did to the 2, and the 2 did to the 1. In fact, it's very possible that the iPad 4 will end up being outdated at about the same time the iPad 3 becomes outdated. Just to add one more thing: If the retina display isn't a huge thing for you, even the iPad 2 is comparable to the 2 and 3 (but the retina display for me is hugely important and single-handedly is the reason why I look at the 3 outshadowing the 2 so much).
That said, just because the iPad 3 has been good for so long, it doesn't mean that you should jump at it now. It's good for those who invested in it when it came out.
So anyway, since I find the iPad 3 and iPad 4 so comparable (and speculatively on the same product life span cycle), I would say you might be better off going with a new iPad 5 if the best deal is what you're looking for. That is, if it turns out to be a decent jump like the 2 and 3 both did.
Not a good buy. Apple's stepchild. Outdated connector.
Better buy iPad 4 after 5 is out. The 4 is the 3 in SE version: Faster processor - and heat problem solved; new connector.
I think, max. two more main updates. Only a guess.
Out of curiosity, what heat problems? I realize I'm not everyone's experience with the iPad 3, but I've never had issues with mine (it gets warm, but I've taken it to the desert on vacation two summers in a row and used it in extreme heat with no issues). No issues at home, no issues when I take it out, no issues ever. I did hear about people complaining about it getting warmer than the iPad 2 by comparison when it came out, but that's all I can think of?