Please look on the seattube and try to find a decal that provides the tubing. A clear photo would be good. It probably says Columbus.
I see Chorus and what looks like a fairly clean merckx - likely early 90s. Rough price estimate on eBay would be $1,000 from a reasonably experienced seller. Deduct fees. Value on Craigslist depends on your location - pricier bikes are often harder to sell. At least $600-700 in most areas.