How to correctly buy and acquire every single project skin and border

Okay, so you got your icons. They're pretty cool. You also got five PROJECT cores in the process. When the Disruption Cache (1500 IP) comes out, you'll get seven more, giving you twelve. These can be used to forge a PROJECT border for one champion using your PROJECT blueprints in your Hextech inventory for seven Cores, or a random old PROJECT skin for eleven Cores (which is only available for crafting after the Disruption Cache comes out). Since you want all the borders, you're going to need twenty one PROJECT cores; nine more than the IP chests can give you.

In order to get these Cores, you need to spend some money on Augment Caches. These nifty Caches have two guaranteed PROJECT Cores in them, one Skin Shard, one Loot (anything Hextech) Shard, and a chance for an Augment Cache fragment. How you get your Augment Caches is your choice. Augment Caches are a pretty nice deal in themselves; they're only worth 295 RP for two pieces of Hextech loot along with a chance for a Augment Cache fragment, whereas Hextech Chest and Key are worth 250 and have a one piece of Hextech Loot inside with a chance for Essence or a Gemstone. However, there are bundles with even better offers. You can buy a ten Augment Cache plus Gemstone bundle for 2950 RP. While each Cache is at full value, you get the Gemstone free. You can also buy an eleven Augment Cache bundle for 2950 RP if you do not care about the Gemstone. Thirdly, you can buy five Augment Caches with some additional Cosmetic Essence (don't know how much) for 1475 RP. Fourthly, you can get the PROJECT: First Strike Augment Bundle. This is worth 8220 RP, and gives you the three new PROJECT skins, eleven Augment Caches, the Recon Drone ward skin, three icons (I think it's the PROJECT Ashe, Katarina, and Ekko icons, don't think Ashe Recon is in there), and the three IP caches if you don't already have them. (Having them might take some RP off the cost of the bundle, I'm not sure.) Lastly, you can get the PROJECT: First Strike Augment + Bundle. This bundle is exactly the same as the previous bundle but you get ten Augment Caches and one Gemstone instead of eleven Augment Caches.

Since you need the skins if you want to craft the borders (which you must do by the end of the event), I'd suggest you buy either of the PROJECT: First Strike Augment Bundles. They give good value for the stuff and give you the Augment Caches that you need. If you don't want that, buy the skins individually and buy the Augment Essence bundle for the nine PROJECT Cores you need. (That will give you ten.)

Lastly, you might get lucky and get a few Augment Cache fragments and get more Augment Caches. This will decrease the amount of Augment Caches you need to buy.