I got a $15 no name submersible that works great. Been running 24/7 for months now on one of my Distributed Folding crunchers. Use a good high flow block and your golden. Also the VIA 1300's are decent pumps at 370GPH and can be had for $18.00. Then you got the Rios that are ok and dirt cheap.
http://www.aquatictech.com/pumps.html