Faction Rep Guide
If you are seriously looking to hit rank 25 with your faction to gain access to the faction exotic quest line for your exotic class item and are stuck grinding away with little progress, here are some things to help.
Faction rep leveling cost by the numbers
Current donation list rep (2/18/16)
5 Motes of Light - 100 rep
25 Weapon parts - 50 rep
25 Armor supplies - 50 rep
4 Special ammo - 25 rep
1 Heavy ammo - 25 rep
25 Materials (spinmetal) - 50 rep
Cost per donation
5 Motes of light Xur - 10 strange coins
25 weapon parts gunsmith - 1,250 glimmer
4 special ammo gunsmith - 1,000 glimmer
4 special ammo with ether seeds Variks rank 1 - 400 glimmer
1 heavy ammo gunsmith - 950 glimmer
1 heavy ammo with ether seeds Variks rank 1 - 250 glimmer
25 materials from vanguard - 12.5 legendary marks
Cost per 1 faction rank
100 heavy ammo from Xur - 33.3 strange coins
100 Heavy ammo from Variks - 25,000 glimmer
400 special ammo from Variks - 40,000 glimmer
1,250 weapon parts from gunsmith - 62,500 glimmer
100 heavy ammo from gunsmith - 95,000 glimmer
400 special ammo from gunsmith - 100,000 glimmer
1,250 consumables from vanguard - 625 legendary marks
125 Motes of Light from Xur - 250 strange coins
I do not recommend using armor supplies unless you have a ton of them because currently we cannot purchase them. The best things I have found so far is buying heavy ammo from Xur with strange coins and Variks with ether seeds. Next is weapon parts from the gunsmith. However, I only buy heavy ammo from Variks if I happen to have ether seeds, if not and I am close to 25,000 glimmer I buy 10,000 glimmer worth of weapon parts.
There are also motes of light from the speaker and I will add that to the list shortly. This guide was made with readily available items in year 2.
100 strange coins = 300 heavy ammo from Xur and 3 faction ranks!!!
If anything looks off give me some feedback and I will fix it (as of 2/18/16 and subject to change)!
Good luck Guardians!
*Edit* You can also trade 5 Black Wax Idols to Eris in the tower for 1 heavy ammo synth.