Wanted: descent tour bike!!! ASAP. Oaxaca

My sister and I decided to start a bicycle tour south from Oaxaca just yesterday when we found a woman willing to end her tour and give us a deal on her bike and gear. Unfortunetely, there are two of us! Having major difficulties finding any sort of used bike here in the city.... any one selling a bike, or willing to reach out and give some advice?
Anything would help!