You will be able to fly pretty much any heli in your "wish list" with a DX6i.  They can be found used for 100 bucks or even less if you look.  Swap meets are a great place to get good deals like that.  A friend picked up a nice used DX7 for 75 bucks at one of the last ones we went to.  Wish I had seen it first as I already own a DX7 and would be nice to have a backup just like the one Im currently using.  However, expect that to be the exception and not the rule as most used DX7's I see are around 150 bucks and up.

Really though, if you like helis as much as you seem to point out in your post...AND it wont cause you or a familiy member to go without a meal...Id go with a DX8.  If nothing more for the nicer features it has.  I dont need one as my DX7 flys everything I own (mSR, mCPX, clone 250, 450, 500 and a Raptor 50).  Its just the DX8 has telemetry so you can tell the state of your battery charge while flying.  Also holds more models and can use a SIM card to store models.  Great to be able to dump your models to your PC and store them in case something happens...you dont have to reprogram all of your models and such.

So...the way to go would be the 8.  But dont miss a meal to get it...because the 6i is inexpensive and like I said will fly all of the helis you ever plan on owning.  It just wont have all of the fancy bells and whistles the 7 and even better 8 will have.

One more thing...the 6i uses AA batteries.  That might be ok for some, but I prefer to at least use nicad TX packs.  There may be a nicad pack available for the 6i and I just dont know this fact.  If so...doesnt matter much then.</p>