I see a lot of people, espacially new players not buying citadel upgrades. This is a little annoying if you have to do it all alone. Here's a lil math for all the "But i have to save for my super awesome 18k weapon!"-guys.
Buy at least the currency upgrades, it will help you and your team.
1. Upgrade: 1800. One gold per second = 1800 seconds = 3 Minutes. That means it pays for a 3v3 team after one minute, for yourself after 3 minutes. (alive time, yeah, you don't get gold when dead).
2. Upgrade: 3600 = 6 minutes. pays for your team after 2 minutes, for yourself after 6 minutes.
3. Upgrade: 4800 = 8 minutes, pays for team after 2 3/4 minutes, for you after 8 minutes.
As you can see, the game must be very very short to give you a reason to not buy at least the first 2 gold upgrades (it takes a while to be able to buy the third one). Not to mention the first upgrade pays for the second and so forth.
Conclusion: Buy cit upgrades. as early as possible. it will help you in the long run. buy currency and exp upgrades early, those priests can wait, they give exp and gold to your enemies and ain't that scary really. hopefully after this post i won't be the one with the cit upgrade award after 90% of games. if you spread the cost out to the team, everyone can get good equip ASAP.
First off...
1800/60 = 3 minutes? No! 30 MINUTES!
But, actually, it's 4 gold each second for each player, so really looking at about 7.5 minutes, 2.5 minutes for each player assuming 3v3.
Doing the full math:
Level 2 = 2 gp extra per second @ 3600 gold = 30 minutes for one person, 10 for all three.
Level 3 = 2 gp extra per second @ 4800 gold = 45 minutes for one person, 15 for all three.
It's still worth it if purchased early in most games, but not an essential upgrade. Getting anything above rank 1 is dumb. If it's going to be a quick game (like fortress) or if your team is great at pushing, don't get it.
Also, make sure it's the people who don't benefit as much from cash who get the upgrades. Regulas and UB should NEVER be paying for upgrades, because it's too important for your team to get the buff as fast as possible. TB especially benefits less from gold than other players, and he should be one of the main upgraders.
EDIT: Removed the stupid 