This is the first and most important question every collector should answer. More specifically, are you in this hobby for the investment or for the enjoyment? I think more people collect Vinyls simply because they like them, but there are quite a few collectors who think more about potential profit.
If you want to collect for profit, or you already are, I advise extreme caution. Many scoff at the idea that the more expensive vinyls on the secondary market could ever tank in value, but the fact is that none of us know what any Vinylmation will be worth in the future. If I were to guess, the original Park 1 and Urban 1 vinyls are most likely to hold their value because they were the first ones made and were produced in smaller quantities.
Even that is not guaranteed.
Chasers and Variants from each series are already more valuable than 'common' vinyls, and with Limited Edition vinyls, the lower the LE the better. The Park Series and other character-related vinyls tend to be more popular (and thus more profitable) than Urban, Holiday, etc.
I suggest, if you want to make a profit, that you focus on collecting a combination of Chasers, Variants, and LE vinyls. Or maybe save full sets of 12 in most series (16 in Animation, 13 in Star Wars) for long periods of time after they're sold out. In theory, the longer you hold onto them, the bigger the profit you will make. Of course, the longer you wait to sell, the greater the risk that the secondary market collapses.
Will Vinylmation collecting eventually go the way of most pins and many other collectibles, with sold out items available for purchase at dirt cheap prices down the road?
Maybe, maybe not.
Predicting value in the collectibles industry is mostly guesswork, especially considering the poor U.S. economy. Don't count on your Vinylmation collection to turn a tidy profit down the road. Hoping for the best but being prepared for your vinyls to lose their value is the smartest attitude to take. If you would be hurt (emotionally or financially!) by tumbling prices, you should really step back and reconsider what you are collecting.
If you want to collect for the simple joy of owning vinyls, then there's little risk. You don't have to worry about any given vinyl becoming worthless in future. All that matters is that it's worth something to you.
Your biggest dilemma will be what to buy! If you're like me, there are simply too many great designs to buy everything you like, or even everything you love. Before you start buying random vinyls, think about what you want to collect.