Currently on line I am unable to find this edition for sale. What I have been able to find was a reference to it in “The Shelley Library.Shelley's Own Books, Pamphlets & Broadsides; Posthumous SeparateIssues; and Posthumous Books wholly or mainly by him. An Essay inBibliography by H.B. Forman.” According to this bibliography this edition is from the early1840s. It's uncertain of the date as there is no date listed in the book and the Bibliographic entry which dates the book as 1840 or 1841 is based on the copy in the British Museum. After the first self published edition, the poem was only available for many years in pirated editions and i'm not 100% sure whether this particular edition is another pirate or not. All of these illegal versions and the first self published edition are worth $$...
This is another one of those books that I am pleased to have found, not just because of the $ value, but because this title has an interesting publishing history contemporary with this edition. From experience this $ value wont necessarily translate into real $ in the near future. It's a long term investment that I now have.