I'm not the most knowledgeable about figures, mainly because it's an expensive hobby that I try to steer away from for the sake of my wallet. Yes, figures get announced months before their release when buyers can make pre-orders. Figures normally do not sell out on pre-order, let alone the first week. It all depends on popularity. For example, Kuroki is not going to sell out. Then look at Shimakaze who recently sold out in less than a day. The pre-order period is your best time to get them, so while you normally don't have to worry about selling out, there is still the deadline of pre-orders. However, oftentimes figures will get production beyond pre-orders but it's going to be months later for the same price. I assume it's just based off popularity. Like, it's really easy to find Nanoha figures because it's such a popular series. So really, the faster something sells out, the more likely you'll get another chance, just not anytime soon. I'll say I've never heard of figures NOT getting more production after pre-orders, and this is most likely due to the ones that don't are the ones hardly anyone cares about. But like I said, I'm no expert so don't quote me on this and figures do eventually stop getting production.
Limited edition figures are another story. Obviously, you should take the chance while you have it if you really want it. It's unlikely there'll be more, but it's not unheard of to get future re-releases. I think there was a limited edition Saber that got like 3-4 releases because it was such easy money. Kind of sad but throwing on "limited edition" makes people more prone to buy but then it's not really limited. I couldn't resist getting this just cause they told me limited edition. Yeah don't remind me about the price...http://www.goodsmile.info/product/en/39 ... r+ver.html
Figures after pre-orders and official release are for sale in the right places, though obviously the older it is, the harder to find. I got mine from actual shops in Japan, but there are a handful of legit (by legit, I just mean not fake) online shops that sell figures. The supply, however, will be in some balance between popular enough to get more production and be carried by the seller but not so popular that everywhere is sold out. A slight tangent, but anime goods sometimes sell out completely with no more production even if they're really popular. Makes me sad.
Anyway, yeah the hobby is a bit different since it involves ordering months in advance. I wouldn't rely on future production, mainly because it's just so much harder to find them unless it's super popular. It's nice to have a shelf of your favorite characters, but space is a big problem and honestly the biggest hindrance to me. Or rather, it's the biggest money saver because I just don't have space. In fact, I just saw a Shiki today I wanted but I literally do not have a place to put her. Money is another huge problem. They're pretty expensive and the shipping adds up. Please spend wisely.
"It was then that I found the darkness in my heart, but I wanted to become a strong person who didn't yield to such weakness." - Nana Mizuki