I think BIN price on landing page would work better. Because they just ignore the first email and any future emails, and if you include BIN in the email , you are stuck with that price. You will forget your price, they won't. But if the price is on the landing page, they will forget the old price, so you can change it. Maybe you can say, today's price is this much, but only valid for today, future price can be more fair and much higher..
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Saying all these, but my emails are never replied, unless they are part of an existing business. I really don't understand why this is the case. But I believe people open those emails, and keep for future reference. So a catchy (but not spammy ) title is a must.
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I prefer direct sale at registrars. I add a very low price, and invite people for quick purchase. They don't. Later they may offer much higher price.
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If people respond, this is not for buying purposes. They don't say you price is high and I can pay this much. They just say something meaningless., like "can you clarify your question".. If they ask price, this doesn't mean they would buy. Your price is 1000, they won't buy. Buy even if it is 10, they will still not buy. If the price is high, domain is expensive, if it is cheap, you are cheap, notyour domain.