" Let me explain in detail. We will just concentrate on the second clause that starts with "Their wines...".
"Their wines have been priced to sell, and they do [sell]. " -- This is the right version of the sentence. Parallelism lies on either sides of "and". you say that "Their wines have been priced to sell" on first note. On second, you actually mean to say that "Their wines do sell". When you combine these 2 notes, you get:
"Their wines have been priced to sell and Their wines do sell".
You have 2 repeating words -- "Their wines" and "sell". So, you replace with a pronoun "they" and eliminate second "sell" as it is understandable that it is meant to sell.
Try replacing "are" and "have" in place of "do" in: "Their wines have been priced to sell and Their wines do sell".