I look for places that have affilates or partners in the Netherlands, or other such relationships. Such would be:
Friesians4USA in Virgina (The Simonetti's are long time board members of the FHANA...however, they are looking to sell off and retire)
Anneke's Friesians in Texas (but she lists outside horses from everywhere)
Legacy Friesians in Oregon
Signature Friesians in Kansas
Old Corner Stables in North Carolina
Wish Upon a Ster in Maryland
Excalibur Friesians in California
The above I've talked with and know a bit about. Here are a few I've no dealings with:
Dragstra Stables in North Carolina
Leyendekker Friesians in California (one of the founding members for Friesians in North America...had one of my favourite stallions, Laes)
Dutch Horse Friend in California
Zylstra Friesians in California
Sea Chanty Farm in Maine
The best places to look, however, is breeders with long time standing with the KFPA/FHANA...major players in the Friesian world! Some (who have websites) would be:
Friesian Dreams Farm in Wisconsin
Friesins of Majesty in Vermont
Knapp Friesians in Oregon (affiliated w/
Friesian Spectacular and former home of the amazing
Clay Maier)
Martindale Friesian Farm in Indiana
Spearmint Rhino Friesian Ranch in California (they are privately offering up practically all their stock and have some amazing deals! Including their 3 Approved Stallions!

)
Black Horse Valley Ranch in California (I want
him!!

)
Another place I can recommend (second hand...I know a woman who bought her foal in-utero here and trains here) is Leeandra at
Legacy Stables in Maryland. Her new website is forthcoming (they just bought their own farm). Leeandra is a reputable breeder and trainer of Baroque and Gaited horses, with the biggest focus being Friesians.
Did I give you enough options?!

Heh...
If you're looking at buying in the states, NOW's the time to buy. Prices are ridiculous for Friesians right now. Especially from private homes! My gosh! Granted, you would need a good eye to buy via this method, but the prices are crazy! Established breeders, trainers, importers are still fetching the same price for their horses, of course.