- The painting is appraised as worth millions.
- The painting is appraised as being worth millions.
- The painting is appraised and worth millions.
- The painting is appraised with a worth of millions.
I think both sentences 1 and 2 are correct, as is followed by an adjective or gerund.
As to sentence 3, is it correct? I think it is, because here worth is an adjective, it is the same as "The painting is appraised and is worth millions."
As to sentence 4, according to Longman Dictionary of Contemporary English, "worth" is an unconuntable noun. But I do see examples like this in The American Heritage Dictionary of the English Language 4th Edition: "stocks having a worth of ten million dollars."
What's more, some dictionaries claim "worth" is an adjective, while others say it is a preposition.