There are several thrift stores in OC. Look up yp.yahoo.com and look up "thrift stores" and you'll find them. I'm in So. OC and the good ones near me are St. Vincent De Paul. The one in SJC does a 1/2 price sale first Saturday of the month (hey, I have dibs on some patterns there ) and the one in Laguna Hills does 1/2 price sales each Wed. and Sat.
When you find a good thrift store, find out when they do their sales. I've found that for a lot of things, they are pretty expensive and they don't count as "thrift" until they go 1/2 off.