Definately get the tensioner changed as its the tensioner that lets go usually before the belt, ford say 100'000 till belt change but disregard that completely, 75'000 is the norm but after 7 years i would change it regardless of miles, i changed mine at around 52'000.
Get the water pump done at the same time too, the waterpump is behind the cambelt.
Price wise an independant garage will always be cheaper but they may not use genuine parts, for a cam belt i would want the real deal.
I did my cambelt myself its dead easy.