Published weekly by expert constructor Peter Gordon, the Fireball crossword is famous for being hard. How hard? Well, in the words of Peter Gordon, if you need to ask, too hard for you! It is not regularly a meta crossword, but does feature a contest or meta puzzle several times throughout the year. Available here for a subscription: http://www.fireballcrosswords.com
Got it. What a hard grid though! For me, the clues were VERY obscure and I had to resort to Google more than I prefer. Amazing construction, I must say.
The grid was hard, but in a good way. Challenging, but managed to figure out almost all the stuff I didn't actually know. Finished my pre-google attempt with only one square that I had no idea about (and guessed wrong).
Got lucky in that my first idea about the meta turned out to be the right path.
If you want help with a meta, feel free to PM me. The more specific you are about what you have and what you want, the more likely I can help without spoiling.
(And if I help you win a mug, I’ll be especially delighted.)