You might want to consider getting a cheap amp and a used HD600.
The 600 is a classic, if you get it you should not need to upgrade until you start to itch for the HD800 . It's still one of my favourite cans I've ever heard.
It looks like it's either the 28th of April on a Tuesday, 2nd of May on a Saturday or 5th of May on anther Tuesday.
@billymav are these times ok with you? Personally I would prefer the Saturday, but the Tuesdays should be fine as well.