I believe the entire earlier line has been reissued with TFA packaging (well, the same packaging the TFA line is using) so you shouldn't have any specific trouble - it's all popular now, though, and the online store doesn't seem to keep the full line in stock for very long.
I really wanted to give this line a try, but the availability just sucks. I can understand when Hot Toys or others do only limited runs of their vehicles, but why do so with a normal product line like this one?
Over here in Europe, the re-release of the older versions in the new red boxes is almost not available. You can only get some of the TFA vehicles, and even with that, it is pure gambling. Like the X-Wing, which was not available in the EU-shops for some time, then pops up again for 2 days, disappears again, and now I "could" order again. "could", because: I think I'll pass and stick with Micro Machines and maybe start adding Titaniums to my collection. Still, this is a disappointment. Not only because I am a sucker for completeness, but also as I would have loved to add the Die Cast AT-AT to my shelf - but getting one seems impossible over here in Europe.
I know I am late to the party and should have started collecting before the TFA-hype set in, but still: these are toys, Disney is huge company, so why not just let the goods flow?!