Armor +1 is the armor's price plus 2,000 gp.
Armor +2 is armor price plus 10,000 gp.
Helm of Teleportation is 5,000 gp.
Pearl of Power is 250 gp.
And don't forget, you will get three uncommon item and one rare item for free, just cause you've been around the block a few times.
I'm pretty much going by the DMG's suggestions. Armors and weapons will likely be at the top of their cost range. Helm of teleportation is at the top, because it's a very potent item.
Also, as far as I'm concerned, all the money for the party can be put into a "Party Pool" if each member agrees. I figure your group has known each other for a while, perhaps has its own guild or something. This way, you can afford to equip yourselves the way you want to be equipped.