About pledge tiers, I've studied Elite:Dangerous KS again and they also have almost half of their backers at the $20-25 tier. Which is the digital price for the game and pretty normal. But..
They attracted 2000 people at the 40 pounds ($62) tier simply by rewarding them with the "name added to game database" thing. For JA:F the first chance to do that is at $200 and you sold it to 5 people. They got $124,000 out of it, you got $1000.

Also they have sold more than 1000 pledges worth 150 pounds ($233) rewarding them with becoming "Elite Founders". In comparison you're offering the chance to have the name on a wall ingame for $500 and only 4 people bought that. They got $233,000 out of it, you got $2000.

You're missing out on a HUMONGOUS pile of cash here, mostly due to simple options being way overpriced and not accessible to more people.

If I may, i'd suggest thinking of a tier that puts the backers name somewhere on a secret "AIM Colaborationists, Sympathizers and Undercover Agents" list. That could be an intel file the AIM enemies want you to locate during a quest and should be priced around or below the $50 tier.
And another tier called "AIM Founders", again a secret file you need to unlock as a sidequest, that would include intel about a few select individuals that pledged somewhere around $200. If there's a laptop interface you could put their mugshots on a "hacked" secret page on AIM's website or something.