Cambelts very rarely fail its the tensioners that let go, personally if it was done at 60k miles with a new tensioner I would leave it, cost more to replace than the car is worth at a garage. Always a gamble as are most things in life but a fair chance that it will last until you part company with the car, hard headed maybe just pure economics.
Neither... you sir, need to get your hands dirty with some of these jobs. The car is worth more than its value to most here, especially if your stuck at the road side with a busted engine at the most inconvenient time. Not to mention the potential for an accident if the car stops in the middle of the road.
Tensioner and roller kit is part of the belt change as its the bearings that fail. Period used to be 80k to Impress fleet managers, but was reduced to 40k due to the number of failures on the bearings. This has nothing to do with the baking plate as the roller/tensioner are interchangeable.
There is a video on DVD from the club shop, and a cam/crank locking kit can be borrowed, loaned, rented bought on ebay etc to make the job very doable diy at somewhere in the order of £80-90 for the cam belt kit of you shop around. Gates, conti, skf where all suppliers to the manufacturer so any of those will do.
No excuse really.