I just ask the tellers if they have any old currency, a few have my number to call in case they do come across something (though I have yet to receive a call).
Sometimes, I ask if they have any of the old "small-headed" $5's $10's or $20's. Most times these are the relatively common late 80's to 95's, but I have gotten a couple from the 50's and 60's doing this. I also try to ask specifically about $2 bills as they don't circulate as much so there is a higher probability of older bills still floating around in circulation.
Occasionally when I am cashing in my reject coins, I will get $100 to $200 in ones and just look through them for older bills, star notes, or other interesting serial numbers. I have found 6 - $1 star notes out of $2000 searched in 2007. The oldest $1 bill found this way was a 1963 FRN. I also have found a few $2 and $10 star notes this year.
I was reading a currency price guide in the bookstore recently and noticed the 1976-I $2 Star note is worth about $75 in XF and $200 or something like that in UNC. So after reading the price guide, I went to the bank and got 100 $2 bills about a week ago. All of the bills were 1976, 2 were star notes, one 1976-I* and one 1976-B*. I don't think the 1976-I* would grade XF. Then again, I haven't tried to learn how to grade currency yet. Either way it was kinda cool to find a note that is worth "apparently" more than face value.
Biggest problem with collecting currency for me is although I can usually find old bills, putting a $100 bill into my collection takes $100 out of my wallet for other stuff. It's just more difficult to justify the cost. Even the largest denomination coin in circulation today still only costs $1.
Well that's enough rambling for this post.
Good luck and hope that helps.
