Amazon has the 30-Day Audible Standard or Premium Plus Free Trial for $0 for the first month. The Audible Standard plan offers 1 audiobook a month (1 million+ options), keep as long as you are a member. The plan auto-renews at $8.99 per month after 30 days, cancel anytime. 

Premium Plus includes 1 credit a month to buy any audiobook, which is permanently yours (even if you cancel the subscription). After the 30 day period, the plan renews at $14.99, cancel anytime.