you can keep checking this
thread
just gives u some information on how to spot them and such
but last i heard, the older 360s are pretty much cleared right now and even the Halo special edition 360s are now running on the newer upgraded chips...
also ask around if its worth getting a 2 or 3 year warranty from FS/BB, last i heard if ur console breaks down, they just sent it microsoft which is something u could do urself
or they replace ur console with a new one on the spot at the stores.....
shop around when u are near into buying one, costco has some insane deals like with an extra game, controller, charger pack etc...
or discounted prices........ the 360 is a 2 year old console, so manufacturers can afford to throw in some good bundles and deals now..