Aqua Medic SP 3000 Niveaumat is less than $90.00. I bought it and had problems with the float being too sensitive, it would cause the motor to stutter and stay on which came close to over flowing my sump. I resolved the issue with a cheap timer set for 1 hour intervals four times a day. For the money and the very basic setup of the device I would recommend it. It only does about 3/4GPH but it keeps up with my 75G just fine. Was the best money I have spent in this hobby to date. I just fill up the bucket twice a week and no worries.
To fail to plan is to plan to fail.