I had them all I guess
- from airport to Bourguiba from departures late at night - 20 Euro
- ditto from departures end afternoon - 50 dinar was as low as I got (14 Euro)
- from airport in the late morning, picking up a cab at departures - 10 Euro (33 dinar)

The other way around
- transfer arranged from hotel to airport 3 am - 45 dinar. It was a normal cab and they seemed to have split the fee between cab and hotel
- cab picked up at Bourguiba 9 or 10 am - once 10 dinar on the meter (gave 15) and once only 7 (that is not even 2.5 Euro! - gave 10).

So the 10 dinar range is apparently a normal price, but good luck getting that if you are at the mercy of the airport maffia.