I find the non camera bags that I customize and pad them well with bubble wrap or foam/sponge reinforced inside as needed, very effective.
I get them from local thrifty shop that has large quantity and variety to choose. Prefer the ones that go as backpack and have wheels in case weight and fatigue of a long day at its end demands. By purchasing from them, I feel good helping in one way or another with some cause and the price is really dirt cheap.
No you may not look cute or shinny much with it but most importantly, these kind of bags, when left alone (In a car or as accompanied), drive a lot less attention (Specially in a touristic environment) form otherwise enthusiastic that need quick cash or want the camera without paying for it
No mater what you buy, think ahead of time for a provision that tripod or monopod can or might be assisted also as you surely need it if photo session is going to be long.