This is one of four Harry Potter Gallery sets. It isn't an actual playset but is instead a collection of minifigs. All of the minifigs were included in other sets but I think the Gallery sets were sold so that people could get the minifigs without needing to buy the sets that included them.
If you look below you will see that I have included links to Amazon and eBay so you can buy this Gallery set but I'll be honest with you - I doubt you will be able to find it. I've never seen it for sale on either source. You might have better luck on eBay than on Amazon but at the same time since you just never know when it might show up for sale.
Looking for more Harry Potter LEGO® sets? You can see the list of all the sets here.
Do you live outside the United States?
Although some items on Amazon can be shipped world wide, you will probably have the best luck with eBay and Etsy. Click here to see how to know if an item from those three sites can be shipped outside the U.S.A., as well as how you can buy items found and have them shipped to you even if the store you buy from doesn't ship to your country.(Clicking this will open a new window so you won't lose the page you are currently on.)
This LEGO® set contains small pieces that could be a choke hazard and is not meant for children age three and younger. LEGO® is a trademark of the LEGO Group of companies which does not sponsor, authorize or endorse this site.