i've been using the lowepro exchange messenger for a while now and i like it.
it fits the rd1 with 50/1.1 along with the 28 and 35 and my ipad (i cut the divider on the outside pocket) and my little bluetooth headphones (did i say i love my ipad), batteries, bus. cards and sd cards fit in the small zippered pocket.
i like that it's light weight and i put micro fibre cloths in the bottom of eash segment in the main compartment to act as both a cushion and to have something to dry the gear in the chance of rain or snow.
cheap and cheerful.