The truth is that I will buy plants anywhere: grocery stores, garage sales, big box stores. But I appreciate good nurseries and there are several I like a lot–two are here in Phoenix, two in Reno/Sparks and one online:
Treeland, Mesa, AZ: http://www.treelandnurseries.com/ (also on Facebook)
Baker’s Nursery in Phoenix: http://bakernurseryaz.com/
Moana Nursery in Reno: http://www.moananursery.com/
Rail City Garden Center in Sparks (great selection of pond supplies and plants): http://www.railcitygarden.net/
High Country Gardens (mail order–home base is New Mexico): http://www.highcountrygardens.com/