Kingpin;130927
I've had limited experience with manga, but with collecting Hellsing, I've found the time between releases to be significantly longer (partly due to the larger pagecount of a manga)… I think, three months maxinmum?
That's a very rough guess.
Of course it depends if they plan to do another or not.
Plus of course a book like
Ghostbusters takes a lot more work on TokyoPop's end: most manga are English adaptations of material that already exists, having been previously published in Japan. They have to translate, rescript, and reletter the dialog and sound effects, but the story and art is done.
A totally in-house work like
Ghostbusters: Ghost Busted requires them to also do the work of writing and drawing the material, which they don't have to do with “real” manga. (Many would say that technically, not having been written and drawn in Japan,
Ghost Busted isn't manga, but is instead a manga-influenced American comic. When it comes to semantics, your mileage may vary)