I have bought from them (Roberts) twice through eBay. They are excellent, in my experience.
My first purchase was a FA 100mm 2.8 macro listed in "good" condition, but was easily "excellent". Shipped well packaged and fast.
My second purchase was a flash shoe accessory (Adapter F). This accessory comes in two varieties depending on how you intend to use it, and one is more expensive than the other. They listed the one I wanted at a great price. Turns out it was actually the wrong one. So what did they do? They immediately shipped me the one I wanted, at no extra cost, and trusted me to send back the incorrect one in my own time and at their expense.
And since this is a photography forum, after all, here is a photo I took using both of these items