Help with Auto Top Off Systems

I will be going away for a week and wanted to get an auto top off system so I do not have to find someone to come to my home every day. Is it for a 29g tank. Is it possible to get a whole setup for around $100 or so?



I do not know the fist thing about auto top off systems so if you have any suggestions please let me know everything that I would need in order to get it to work. I do not need anything fancy, just something to get the job done.