According to the search results, the value of a Tombstone Ghostify in Adopt Me varies depending on the source. Here are some estimates:

• It is currently worth a little more than the Crow and a little less than the Neon in Adopt Me Trading Values.
• A Tombstone is worth a FR Frost Dragon, or 2 FR Monkey King, or even MFR Unicorn according to Adopt Me Giveaway.
• The Tombstone Ghostify is worth at least three Lanterns, or an Owl. In some cases, there have been reports about players getting Frost Dragons for this item, according to Player Assist.
• The Tombstone Ghostify costs 2,500 candies during the Halloween event, but it can now only be obtained through trading.

Its important to note that the value of items in Adopt Me can fluctuate over time and may vary depending on the individual trade.