Smannesman: Quick off-topic question, how do you buy it?
Do you have to use the Bioware store?
GameRager: When you load up the game in PC/360 a screen comes up with available DLC and how much it'll cost in microsoft points/etc. Picking one of them opens a buying window to buy and download the DLC in either the 360's download manager using microsoft points or whatever the pc equivalent is....didn't buy PC dlc ever though so it may be different.
I would buy the new game copy though and not used as a new copy comes with a code for activating the Cerberus Network(free DLC packs and some other stuff) which alone is worth more than the 10 extra it costs for a new copy of the game vs a used copy(the code is worth maybe 20 bucks or more in DLC alone).
EDIT: Brand new 360 copy is around $40 american, a used one is $30 american.....the new one tho as I said above is the better bet if you are going to buy DLC anyways.
I bought my used copy from GS for less than $20...