Local Coin dealers. Local Antique mall.
Local online auctions (There is one site that has the warehouse a mile from my home so if I am looking at something I can go and look at the exact coin before bidding.)
I have got 2 hawaii silver certificates for $12, Seated Liberty half dollars
for $15, and some proof/mint sets. I got 2 1996 mint sets (One W dime) for $12, 2 1987 mint sets for $10 and 1999-2007 proof set for $120.