I use a medical infusion pump that I bought off of eBay for about $52, plus the tubing sets for it that were about $45 for four (it only takes two at a time, but I bought a spare set). You can find the information about what I bought here:
http://www.aquaticplantcentral.com/f...tml#post486616
So far, I think that it has been one of the best things that I've ever bought for my aquarium. It has made fertilizing the tank something that I basically never have to think about. All I have to do is make sure that the containers of fertilizer still have some in them (the ones that I use can hold enough for a month). I use the PPS pro fertilizing method, so it takes care of dosing both the macro and micro solutions automatically. I feel that nature is being more accurately duplicated by having the nutrients available 24/7 rather than being dumped in all at once every so often. I love it.
Just my two cents.
Andy