The marks that you are able to obtain per week is set to 100 which I and many others beleive is too low. It takes 150 in order to obtain a weapon and for newer players who have bad luck on getting legendary engram drops or no luck from ranking up In the cryptarch or vanguard and getting g Rares out of the packages, buying a gun is the only way to go which is why I suggest that bungie raises the cap on the vanguard and cruciable marks to 150 per week rather than 100.