Camping Equipment in Budapest

Hi!
My friends and I are coming to Hungary for a festival in July. But we don't want to take camping stuff over with us.
Can you recommend any camping shops in Budapest/Lake Balaton? x

Which festival? I ask as there are many very cheap housing options around Lake Balaton that are not well publicized and you might avoid camping all together. The art festival around Kapolcs is one exception, there camping is quite common.