You can get peristaltic pumps pumps from ebay for pretty cheap, I got a "Aspen" peristaltic pump to pump water into my "sump" in the loft for the original scrubber I had, got it cheap on ebay and has worked continuously 24x7 for 9 months, the Aspen one was designed for air-conditioning units to pump condensation out, but works perfectly for my needs (pumps at a rate of 6 litres/hour), the only other thing you need would be a decent electronic timer, that's what would cost the money.