I no long do this since I moved to the Caribbean. I would ALWAYS go to the casino only to by bags of dimes and halves off those coin counting machine. (They would use the cents, nickels, and quarters for their voucher redeeming machines) They loved that I did this because they didn't have to pay to ship them out. I even had one of the cashiers regularly call me when the half bag filled cause it didn't happen often. This is, IMHO, the best place to buy bags or coin. I don't know how many times I bought from them, but I was never skunked....ever.
And like stated above, they are around to buy coins as they see/find them. The head cage manager told me a story about a bag with LOTS of silver quarters in it. I wasn't that mad because they won't even sell me those bags because they reuse them in thier voucher redeeming machines.
The casino I frequented was Hollywood casino Charlestown, WV and Grantville, PA.
If you have the opportunity to buy from a casino, do it. Like I said, I have never been skunked on dimes and halves at these casinos. My first ever Barber dime came from one of those casino bags.
Hope this helps, and good luck and happy hunting!
Mike