Quite honestly price-wise you’re going to get a better deal online. I’d stick with a reputable place like B&H Photo or Adorama Camera though, especially if you’re considering ‘gently used’ glass. I’ve also gotten some good deals through Amazon (which is where I found Adorama in the first place). Make sure you read all the reviews, and I wouldn’t be afraid to ask specifics here since someone on the forums has probably used what ever lens(es) you’re looking at for either system.
For camera bags, personally I ended up with a backpack designed for the purpose. It’s got foam thingys like an over the shoulder bag, plus lots more space (and pockets). Tripod straps to the bottom, and away I go. Another nice thing about a backpack is that I don’t think it tends to get in the way quite so much when you’re walking around and shooting.
