The $159.00, round trip price you are talking about is a Limo, more than likely, with STS Sanford Transportation. This is the company, and his father's company, that has left numerous families stranded at WDW on the return to the Sanford Airport. There are posters on this board who still haven't got repaid by these companies.
I would advise you to seek a company that would give you better service and you can find them on the Sanford Airport web site.
The ride to WDW is about 1 hour and 50 - 55 miles.