Bruce, with shipping to the UK quoted as "$66.45 USPS Priority Mail International", you are almost certainly right. $90-$100 is the norm including case weight for a C to the UK by Priority mail, assuming sensible packing....Downside is that I don't see mention of the case which can be a deal breaker...
Does not sound unreasonable....especially if you have fully engraved it.I need to sell my Conn NWII C tenor, sadly. It is a near-perfect 203k in silver plate with the best overhaul you can get from Charles Gray, the sax whisperer. I am not sure how much to ask for it. I was thinking $550? That one is gorgeous, but I vastly prefer the later horns, although they are super rare.