I think this price may be an aberration as there appears to be some type of low-income subsidy in place. The SD Lookup listing says that a qualified buyer must have an income of 44K to be eligible, 50K for 2 people.

http://www.sdlookup.com/MLS-080050561-6203_Liberty_Pl_Carlsbad_Ca_92009

Even priced at 232K, seems like a heavy financial burden for a person or family at that income level.