The words, limited edition, are a noun. Usually, you need an article for it. For example,
(1) This gold watch is a limited edition.
(2) This gold watch is limited-edition.
I discussed this with my non-native English speaking friends. They have different opinions about it. Some said that the article is needed and others did not agree. I am not sure who is right.
Is it OK to use it as a compound adjective as in (2) when the article is omit?
Please answer my question. Thank you very much for your help.