As far as the corners go... every place sells the same kind. It's kind of a shot in the dark as to whether or not they are going to leak on you. My first set the passenger side started to leak after a while but not the driver side. However the second and current set I have neither one of them leaks. So just find some on Ebay and when they arrive make sure to seal them up real good with clear silicone to ensure that they aren't going to leak at the carwash and such.
oh cool! i 'm like 20 minutes from this place. i didn't know they sell on ebay. hmmm have to go check out their sale inventory.