By default all colours can be applied to your Javelin. You can also get skins/armor styles and such from some missions and they aren't purchasable at all. The purchasable cosmetics (with both ingame currency and purchasable currency) - we have no idea about cost on yet. But there are lots of ways to get A LOT of ingame currency fast, especially with the alliance system with rewards you with coin based on how much others on your friends list have done; so if you have a bunch of people on your friends list playing you'll get a bonus amount of ingame currency. Devs also said they start you with a good amount of this ingame currency too.
Currently all we can do is speculate on the cost of the shards and how many shards may be needed per cosmetic or cosmetic set. If the MTX do launch with the game tomorrow then I'm sure that these will be a part of the discussion - probably a very vocal part of the discussion. I can see a full cosmetic armor set being $10 and then maybe each part is $3 separately - meaning you'd save $2 if you bought it in the pack rather than separate. The shader materials and vinyls I can see being anywhere from $1 to $5 each depending on the rarity, looks and such. What is good is that you can preview and see what the things you buying look like before you commit too.
And like I said, the ingame currency seems plentiful, especially in the endgame so the shards/$ are just an option for people who want the cosmetics quickly to style their javelin a certain way.
I'm betting your looking at $15 to $20 for high end cosmetics and 5 to 10 for everything else. I'm looking forward to finding out more tomorrow from the people who have access to it, but my money is on prices being to high and the in game time being a time consuming grind.
If you can earn everything in a reasonable amount of time, that would be a first for games. I know Apex and Fortnite are free but Call of duty shares the same pricing and it isn't, and I fully expect to see Anthem follow the exact same pricing at first to try and get away with it. Apex also has a slow grind, so I also expect it to be similar. Again I know it's free to play, but I really don't think matters much to EA when they have people already used to these types of mechanics and pricing on other games.
I also dont think you'll see anything under $3. I guess now we wait and see. Should be interesting. Hoping for reasonable pricing so I can give them cash.