I'm currently drooling over Pukani from reefermadness.com and anything from Bali. Beautiful and intricate stuff. ( Champagne taste - beer budget. )
Some Kaelini has great shapes. Most of what I've seen is just tables and ledges though. If you are there when they open the boxes, who knows what you might find. The colors of coralline are amazing. I even got some yellow.
I found some great Tonga Branch for my 8 gallon Biocube. Very intricate with a lot of arches. Most of it's pretty crummy for nanos. I looked at hundreds of pounds over months before I found the one piece I wanted.
Haitian is nice rock. Great for nanos with lots of caves for the fish and ledges for coral placement. I like Haitian: got purple sponges and bright yellow seasquirts on mine along with some button polyps.
Precured and packed with life from an established tank that was taken down is GREAT.
Okay.
My advice, finally: Buy it local. For a nano you really need to be able to pick and choose the pieces, period.
My best advice: Make a 4 sided cardboard box to the same dimensions of your tank- bottom, back and sides. Cut the sides down at an angle from the top-back to the front so you can peek in at the sides. Get some double-sided tape and stick a piece of heavy duty, black trash bag to the cardboard to make it waterproof. Take this with you to the store and stack your selected rocks in it. If the sales person knows what they are doing, have them try a few arrangements. If they look at you funny, fix them with a steely stare and tell them that you are also setting up a 500 gallon reef. That should do the trick.
Buy all your rock at once. Set aside a LOT of time to make your selection (bring a sandwiche and a six pack of Coke LOL).
You will save yourself a TON of money not buying the wrong rocks or more rock than you need, and you'll get some great ideas for aquascaping.