The pair of shoes in your picture were actually made by a fan on deviantArt. They were made by drawing on white canvas hi-top sneakers (NOT brand name Chuck Taylors) with Sharpie markers.
The shoes Luna wears in OotP are a pair of brand name Chuck Taylors (made by converse) with the logo painted over. The original Chucks were originally available from a website called Office Shoes (
link), but they quickly sold out and have not been brought back in stock. Whether they plan to brign them back or not I do not know.
I don't know of any other way to find these shoes. Some people have had luck with eBay, but you have to continually check back as items on eBay come and go. Your best bet may be to make your own pair. The creator of the pair in your photograph sugested using painters tape to keep the lines straight.
