You'll be able to get $10 and $20 from Borgata and Taj -- both in the poker room.

Caesars has a $20 available on its tables (check the Asian area). Plaza used to, still might - havent been there in a while.

Other casinos (Marina and possibly Plaza) may have some of the $10 or $20 limited edition chips available as well. There's a procedure you might have to go through to get them. Talk to the cage person..