Hi Jdb
We went to Tunisia last month, and after reading the posts on this site, decided to go with our own airport transfers - I am so glad we did.
At the airport there are loads of taxis, we arrived after 1am, and there must have been about 20 or 30 at the rank. We agreed a price on that occasion (we were going to Sousse). I think we had arrived got settled in and possibly were asleep before the tour coach with others from our flight had arrived!
On the way home there was a taxi rank at the top of the road, and we had reception phone up and call a taxi down. As this was an evening journey we just checked that he had his meter at 0.35, and away we went, this trip was particularly cheap.
When you are out in the resort, every second vehicle seems to be a yellow taxi, so no problems there.
Our taxis including tips cost us under 50TND (there and back), which is about £22. The tour operator wanted £60 for coach transfers for this!
Have a lovely time whenever you are going.
regards
Marina