We tried a few different places and they had all doubled their price, they all had lots of motorbikes available for rent so its not like there was a big demand for them.
Finally after hearing that yet again the price was double due to tet we decided we wouldn't bother but as we walked back to the street one of the moto taxis was there. He had listened to our full conversation and rather than his normal "you want moto" he said "You want bike? you rent mine". We talked for a bit and agreed on a price that was a few dollars less that what the shops wanted. His bike was new unlike the old bikes the bike hire place had. He called his friend who arrived on another bike which my 2 friends hired. They gave us their helmets and then rang another friend who arrived and give us another helmet (3 of us and 2 bikes). We agreed to meet them in the same place the following day at the same time to return the bikes. We paid them and the 3 of them left smiling all on the one bike and no one wearning a helmet.
We spent the day riding around Mui Ne visiting the sand dunes, sandboarding and stopping at some fishing villages.