最好用The painting is worth 5 million dollars。
be worth后可直接跟名词、代词或动名词。如:The picture is worth $ 500. 这幅画值500 美元。The clock is hardly worth repairing. 这台钟简直不值得修理。What is worth doing is worth doing well. 值得干的事就得干好。注意:其后可接动名词,不能接不定式,且接动名词时,总是用主动形式表示被动意义。
而be worthy of 后面跟具体的钱数 不多见。不过我认为也对。
如:Their efforts are worthy of your support. 他们的努力应得到你的支持。
Her behavior is worthy of praise. 她的行为是值得赞扬的。