Why are you selling it? I find the C8 to be a great all-'rounder to have at hand, particulary if it is Fastar compatible...
As for the price, I also agree with the sentiments posted, sold in AU (retention of value is higher here then in the USA).
Piggyback has no intrinsic value, but the wedge is a prized commodity. The SCT Crayford is a "nice to have", but to be honest, I've not used mine much. Collimator is a bonus (assume it's a Hotech?)
Good luck, I might be PM'ing you soon...