If you want a full collection of Amiibos, it might just be a good idea to make sure you have the first selection of characters released. Nintendo has confirmed to Wired that a few of the lesser known ones will be taken out of production after they've been sold out to make room for new ones:
"We will aim for certain amiibo to always be available. These will be for our most popular characters like Mario and Link. Due to shelf space constraints, other figures likely will not return to the market once they have sold through their initial shipment."
Some characters like Marth, Villager and Wii Fit Trainer are already somewhat hard to find with prices skyrocketing on auction sites. And they will most likely not get cheaper after this announcement...