Regarding age: experience, character of glass, evenness of glass thickness and opacity, characteristics of pontil mark, characteristics of the lip finish, similarity to manufacture and appearance of 1960s-1980s Clevenger glass. Also the amber tone is very much a modern one...
Value would be in line with that of Clevenger glass products which would be anywhere from $5 to 50 for most pieces (although scarcer and fancier objects fetch more)
If you could pin the manufacture to a person or company, that could help immensely.