I will only buy big box Clematis if they are blooming so I know what I am getting. I have been burned...I very rarely shop big box stores.

I've purchased clems from various sources, including Walmart, Costco, my local grocery store - you name it (aside from the nursery and a few by mail order). But they were all tiny things and cheap!! I doubt any was more than $4 - Costco's might have been $7 or 8 but included 4 plants!! And they all grew on to be fine vines and remarkably, all true to name.

But $20 for a random, NOID gallon seems excessive to me. My nursery (which carries superior stock) barely charges that much for their well identified and not run of the mill clems.

I would only purchase if I did not care what the outcome was. And I am too picky about my plants for that!