there aren't a lot of appraisers in the phonebook nowadays that can tell you for sure what something like that could be worth. regarding celtic, was it found on Irish land of Scottish, Welsh, etc. were other artifacts with it; if it was part of a burial mound with some other items that may increase the value. the iron age basically started around 800 to 600 BC and that was in central Europe (the Gauls of France could be included in Celtic bloodlines far enough back). Ironworking spread across Europe along with the Hallstatt cultures. it eventually ended up in Britain and then found its way into Ireland, Scotland, even Wales. once iron gained a foothold most never went back to bronze. a lot can be told by the designs on the weapons. is there an anthropomorphic (spelling?) handle, something that looks like a human figure? are there swirls (Keltic knotwork); or maybe something that appears more triangular or cuboidal interlocking and weaving (keyworks). some researchers can date your piece incredibly accurately if there are any clues like this. the kelts were a diverse group; different areas, different styles, although this is no hard fast rule. two of the greatest finds of keltic burials and weapons were at eastern France in Vix (golden pieces); also a presumed warrior-king's (chieftain) grave at Hochdorf, Germany. so it may be from Europe, or Ireland or Britain. do you know where it was found and what it was found near? sorry so long, don't get me talking about my stepdancing....