used engine

Hey folks. I am debating the timing belt change at 135k miles. They want to charge me $400 and do the water pump etc at the same time. Can't I just get a used engine for around the same price if the belt goes?
Any advice is appreciated

omg, lots of $$ i had my timing belt water pump front crank seal and cam seals plus both belts at 250, lol =)

damn... I paid 400 bucks for my aspire with only 36000 miles