I think you can get a shared taxi (sherut) at the border that would take you to the central bus station in Jerusalem. From there take a bus or sherut to Tel Aviv, then a taxi to your hotel. I'm not sure you could get a private taxi at the border that would take you all the way to Tel Aviv, or if you did, the cost could be prohibitive. Of course, you can always ask when you get across the border and then decide. Forget about the train - the station is not conveniently located in Jerusalem, the trains are infrequent, you have to change trains mid-journey and the trip is twice as long as by bus.