Character Innate Wealth By Level System

1) At every level, look at this table: http://www.d20pfsrd.com/classes/character-advancement
Note the expected PC wealth at that level. Multiply by 0.75.

2) This number is now your innate character wealth for the level. You can now use it to 'buy' effects from magic equipment that become innate to your character. (Ie You pay the cost of a magic item and you then gain its abilities without having to wear or own the item)
This has a few caveats:
a) The boost from the item has to be permanent. No items with limited uses. (Limited uses per day is fine)
b) You can't spend more than 50% of your innate wealth on a single bonus.

3) Every level up, your innate wealth budget updates. You can reallocate up to 1/3 of your budget into other stuff when this happens.

4) If you buy stuff like magic weapon or armor enhancements, it's assumed you get the ability to apply that enhancement to anything you equip. If you find a magic weapon/armor that has a different enchantment than your innate bonus, then when you wield it, it temporarily replaces your innate bonus and the abilities don't stack (but it takes the higher of the two enhancement bonuses).

The trade-off:
-Magic items are now much harder to buy in-setting. You can't just walk into the nearest market and buy a belt of giant strength or something.
-Magic items you find are also harder to sell. Larger shops will probably buy them for half their price as normal, but smaller communities might show no interest in what you're offering.

-How this interacts with magic item crafting: Undecided.

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Beginner tips:

-If there's a wondrous item that already does what you want, then that's easily handled.
-For other things, go to http://www.d20pfsrd.com/magic-items and ctrl+f down to 'Table: Estimating Magic Item Gold Piece Values' to get a figure for how much a bonus will cost.

Magic weapons and armor:
This system is a bit more complex.
Weapons and armor prices work on their 'bonus rating', and different enchantments on them can increase their bonus rating.

-Enhancement bonuses are flat bonuses, and for weapons they increase hit and damage, for armor and shields they increase AC.
These go up to +5 at most.
IMPORTANT: Equipment must have an at least +1 enhancement bonus before any other abilities are added.

Then, extra abilities either increase the bonus rating (no higher than +10 total) or add a flat increase to price.

The total enhancement cost is equal to the bonus rating squared, times 2000 for weapons and 1000 for armor/shields, plus any flat increases.

http://paizo.com/pathfinderRPG/prd/ultimateEquipment/magicArmsAndArmor/weaponSpecialAbilities.html
http://paizo.com/pathfinderRPG/prd/ultimateEquipment/magicArmsAndArmor/armorSpecialAbilities.html

So for low level characters, here are some very safe purchases because you need them to build onto them:
1000g to improve the AC of armor or shield by 1
2000g to improve the hit and damage of a weapon by 1. (The hit bonus doesn't stack with masterwork)

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Please keep a record of the bonuses you buy and their prices somewhere on your character sheet, like in the statistics block on the last page. (If you have a familiar/animal companion already taking space there, then use another empty box)