New character, Dungeon Master and what’s for sale Magical debate

As my adventure’s coming to the end and I’m starting to think what magical goodies I’m going to ‘buy’ for Vogir, I’ve come to the realization that we haven’t really set any rules for any of this stuff.

How about this:

New characters: I’m not sure about this. They certainly should be able to choose whatever they want… but… They shouldn’t really have much as the characters that have ground their way up the levels. These characters won’t have had the option to choose their magical items so should offset that by having more. I can’t find any rules about this so need some help/criticism/debate.
(I always assumed the 'character builder' on your PCs gave you a set amount...?)

Dungeon Master bonus: An equal amount of gold of the average Party member total got is allocated to the DM who can then spend it on whatever he chooses. (No limits).

Buying: As an easy rule, why not say we can buy anything of half our experience level or less (assuming enough gold to afford it)?

Selling: Sell whatever magical item you like for 1/5 it's book value. (Or sell it to another Party member for whatever you agree on.)