So after grinding my second character from rank 3 to rank 14, I managed to pick up 2 coins in story mode - one from the winter kell and one from a gold chest on mars. I picked up another doing engrams and picked up another 2 doing public events on friday + saturday as both my characters. That left it at about 11pm on saturday, needing one coin more to get ice breaker, with only a few hours left.
I then proceeded to grind the heck out of the strike playlist. First 5 strikes I did i returned to the tower, more engrams than I could carrry and decrypted the lot.... Not one single coin. This was about 12:30 and time was running out. I went back into the playlist and did 3 more strikes and got a boat load more engrams. Went back to the tower and decrypted them ....
And proceeded to get 1 strange coin out of my engrams, then another out of the cryparch package I got for leveling up. Wait hours for one and then two turn up

Long story short, I got ice breaker, but by god was it one of the most hard earnt exotics I've got. Some just fell into my lap for doing the nightfall and others were part of the exotic weapon bounties. This however, was playing pretty much solid most of saturday afternoon / night and all of friday night all for 6 freaking coins.
God knows why this game doesn't have a currency exchange that lets you swap say 10 vanguard marks for a strange coin and lets you trade in vanguard marks for crucible marks so you can buy armor from the faction vendors when doing PVE.