I am interested in all the older Nichirins, but shipping costs from Europe are ridiculous. As to collectibility, everything is "collectible".

I do not notice much appreciation in value of koi magazines. Perhaps there is on an inflation-adjusted basis for the really old issues before counting the shipping/postage costs. For value appreciation, I think Beanie Babies would be a better deal. You can find them for less than the original retail, nicely preserved in special bags with tag protectors included! Kids love them... as toys.