My experiences with the Eheim twin were not as good as others have said. The augers were constantly jamming and the batteries did not seem to last. I switched over to the Rena feeders and have been very happy. No more jamming and no battery to change.

I bought 2 $3(yes three) ones off eBay, I was going to set them up to have each one feed once a day, but set one up for a test and it hasn't failed since. I'm using the small pellets, this thing has fed twice a day for almost a year now, only fails when I don't look at it for awhile and it goes empty. Original battery's too.. they came with it.

Anyways, all these fancy features and stuff tend to be what break on the pricey ones, and battery life, etc. So far, I'll put out a +1 on the cheapy's,.

Looks like the price went up to $9.99, might be able to find more, but this is the model I'm using.
http://www.ebay.com/itm/Auto-Automat...ht_4078wt_1270

never bought a auto feeder I built one out of scrape products from work once I figure out how to post a picture with my Iphone I will show you it