Personally, I've never found it too hard.
I originally began buying minimates from brick-and-mortar stores. I think I actually got my first ones from a Target, back when they had those two packs that re-released earlier figures. Then I started finding packs at Wal-Mar, my LCS (The only one in my area) and Toys 'R Us. From there, after researching a bit online, I started finding out about Suncoast and Tower Records, and so my search expanded.
However, recently, all these places have stopped stocking them (except for the TRU, which just recently started stocking them - the last time they did were the Street Fighter four packs). Thankfully, around that time my access to online shopping opened up since my mother found it a lot easier to order online than deal with traffic and driving around.
I've gotten quite a few exclusives - the Giant X-Men set, the Iron Man 2-pack, Super Skrull and Clobberin' Time Thing, Sauron, Prof. X and Magneto, Elrond, Stealth Iron-Man two pack, and the Union Jack pack. I've also seen quite a few of the others in stores, and the only real reason I never bought them was a lack of funding at the time.
Like I said, it's never been too hard for me. Sure, the occasional frustration pops up, such as not being able to get a Thor minimate anymore lest I pay $25 for two figures. Or missing out almost entirely on the DC minimate sets. But it's just part of collecting - you don't always get what you want.
And that's the thing to keep in mind - nothing is GUARANTEED to you. No matter what anybody says. I buy things when I can, and since this is a hobby, rather than a necessity, it doesn't bug me too much when I miss out on something I probably didn't NEED anyways...