I just bought my first coal stove, the Harman DVC-500. I paid $3700 for the unit on Long Island. Hardest thing to find, I bought the last one on the Island it seemed. To me, after tons of research the Harman seemed the best, not the cheapest, but the best from an output, looks, reliability, hopper and ash storage capacity, and many other metrics. While there may be less expensive units, the Harman is quoted as being the top of the line. No doubt the other products are good, I chose the Harman.
$275 for the pipe? Mine came with the square pipe to get to the outside world. They wanted $300 for Stainless Steal Tee, 18" of riser and an elbow. Home Depot has the same config in galvanized for $50 but for sure wont last as long.
As far as the Hearth Pad; I've been quoted a pre-manufactured pad with stone finish and wood trim form $375 to $600 depending on complexity. I'll make my own tile hearth as many have suggested. If you dont have the time, skil, etc, perhaps a pre-made unit is right for you.