Last update on New Mexico's sighting forum is 2/10/2010.........
Even if they're sighted, the box is probably written in Spanish anyway xD
Don't know about New Mexico but here in Minnesota, Reveal The Shield line (Jazz, Tracks, etc) can be easily found at Kohl's. You can also try KMart or Walgreen. Kohl's price could be high but they always have sales (or just simply say you forgot your coupons and usually they will give you discount). Generation, Hunt For The Decepticons, and Power Core Combiners line can be found at common retail stores such as Target, Walmart, and Toys R Us. If you have Meijer there, they may have some stuffs and good deals there, too.
No Meijer here sadly, they have awesome prices! I did speak to the guy, and I know he is specifically looking for Jazz and Tracks, so I will start with those. The Hasbro website is sold out of both, so I have a feeling it might be hard to find. I'll start looking around at the places you suggested though (my mother loves Kohl's so I know she's got some coupons stashed away), because it would probably cost less. But the other lines you mentioned, were those released in the UK?