Shopping for Diaper bag

I've been looking for a diaper bag...a tote with external pockets to be exact.Something I could still carry as a shopping tote when my younger daughter is old enough and I no longer need to bring her stuff out.

Saw three totes from Agnes.b, price ranges from $295 to $345,but they are in nylon material, two with leather handles. I am not sure if I want to spend that money on a nylon tote anymore? Since I've owned a few prada totes before, and sort of regretted spending that kind of money on that kind of material. Agnes.b is cheaper, but still is it worth it? nylon material?

Also considering buying LV Totally PM in Azur($1300+). I would prefer to get Totally in Damier Ebene,most likely the MM size, but since it's not out yet,I am still in dilemma. Should I get a Totally PM in Azur first, then another Totally MM ($1700+) in damier ebene when it's out...probably next year?

Or just settle with some cheap M.E.L. PVC totes? Or Le Coq Sportif's nylon 2-way tote at about S$69.90?