I charge $200 PFH on ACX. 12,000 words is about 78 minutes, so you're looking at $267 for prepped, recorded, edited, proofed, and mastered audio (read in an engaging and entertaining manner) that meets or exceeds industry-standard quality. I deliver one file per chapter in mp3 format.
Here are samples:
http://www.audible.com/pd/Sci-Fi-Fantasy/The-Dragons-Bond-Audiobook/B00RB0C81G/ref=a_search_c4_1_1_srImg?qid=1449931010&sr=1-1
http://www.audible.com/pd/Sci-Fi-Fantasy/The-Eye-of-Mezitlan-Audiobook/B017JAJDZ6/ref=a_search_c4_1_2_srTtl?qid=1449931010&sr=1-2
http://www.audible.com/pd/Self-Development/Writing-Deep-Point-of-View-Audiobook/B01K7TNDTI/ref=a_search_c4_1_1_srTtl?qid=1471606830&sr=1-1