Among the cars over 3000lbs, how many of them cost less than $30000?
over 3000lbs refers to weight > 3000; cost less than $30000 refers to price < 30000
SELECT COUNT(T1.car_name) FROM data AS T1 INNER JOIN price AS T2 ON T1.ID = T2.ID WHERE T1.weight > 3000 AND T2.price < 30000