I have one of these and I no longer need it. You could have it for $40 shipped. It's not waterproof, but it comes with a rain cover. It has padded laptop pocket, I think two internal pockets and two or three on the outside. The nice thing is that it converts to to a shoulder bag and you can't even tell it's a pannier. The mounting mechanism with all the metal parts remains on the bike and the bag is attached with two zippers to the mounting plate and then secured with two straps. The not-so-nice thing is the zippers: it's a bit pain in the neck to attach the bag with only two hands

Drop me a PM if you're interested so I'll dig it out, see what the condition is and snap some photos for ya.