i've bought a couple sets of those at the local Sport's Junkie for $7 a pair. They are heavy, but okay and convenient, but I've already broken one - the nylon/plastic just isn't all that strong, and i also got some gunk stuck in which i figure prevented the spring from fully engaging back, so i slipped off the bike one time when it disengaged.
Also when they are wet, the plastic nubs for grip are pretty much useless too. I usually wear my converse while riding, and when i am on the bikes with these pedals I really have to be careful not to push forward on them else I'm off pedal.