Just got to show up at the right time when someone cashes some in. Or some banks will order boxes for you, but with a possible fee depending on the bank.
I do not go out of my way to look (I only pick them up for tolls, change, etc) but I've never encountered a bank that "never" has them, be it from customer exchanges or orders.
One day I had off work, I drove to every bank within a certain number of miles from my home and asked if they had had dollars I could buy. I wrote down who did and who didn't and then what I found. I'd recommend trying something like that, or making friends with a bank teller you have an account with and see if they'll order you a box. I prefer customer wrapped rolls (CWR) as they've given me the best finds.
When you do get half's make sure to look for Doubled Dies, not only silver. I got a nice 1974-d Doubled Die Half out of the rejects from a silver hunter. Most people don't look for the DDO's when silver hunting.
it's a crap shoot here if they have half's or not, I've had more luck with Bank One than Fargo, so it really depends where you are I bet.
do you know of a site that has a good visual list of DDO's? also what years would be the most common to have these DDO's
Go on the NGC website and you can look up their VarietyPlus list. It shows you all coins of every denomination that they recognize for having a variety, along with a very clear, detailed pic of the variety. http://www.ngccoin.com/coin-varieties/
