Buy a car?

Hello today I looked at an Audi 80 2.0 E (115 ps) year 92. Seller said timing belts should be changed (150Tkm down). What costs come to me with the machine ? Read again and again what from 100- 500 € but that big the span can not be there after all or ? How does it look like to do it with yourself, is this possible or do you need special tools ? Then I looked at the oil cover and can actually find nothing but the seller meant only: “the w And he pressed on it on the cooler hose (so it was not hard) Then I talked to 2 car mechanics and got 2 completely different statements: A says: Timing belt change really costs money and there is white stuff in the oil cover, head seal through and rather finger off the car. B says: Timing belt change costs 100€ +50€ material and the white stuff comes therefore that of the dare What should I do Buy or rather fingers away ?