The website that I've been purchasing oolongs from the longest is run by a wonderful Frenchman named Stéphane Erler.
He finds the best high mountain oolongs, and in the past year, many of his teas have been really noteworthy but his Da Yu Ling teas have been particularly phenomenal, comparable to the Zuo Wang Lishan above, albeit more expensive.
I encourage you to visit his site and delve into the wealth of his incredibly fine curated teas.
I love the folks at Floating Leaves Tea and have gotten many great teas from them last year, including a truly incredible bug-bitten Huan Shan and a wonderful Lishan Special Reserve tea.
Both are sold out, so I strongly suggest that you get on their mailing list and jump on their special reserve offerings when they come out.
Right now, they are still offering an excellent Shan Lin Shi.
Since their move to Taiwan from Washington State, their contacts have deepened and I expect many great teas to arrive from them.
Important Note: If you click on any of the above links and they are no longer working, just go to the home page of any of the websites to find their latest offerings.