Get your own books converted (bound) as hardback ?

I'm not sure they exist in hardcover. I think her website has a list of editions, so you might want to go there to double check.

I have the omnibus edition, and I definitely don't recommend it unless you want to get it converted to hardcover. Big, heavy, and floppy are not a good combo in a book.

Doesn't seem these ever existed in hardback.

http://www.fantasticfiction.co.uk/b/anne-bishop/

Lists editions and it seems only her more recent titles have had the hardback treatment. You could write to ROC and see if they have any plans to reissue the early titles in the series in hardback.