Costco is inexpensive.
I don't have a problem with big box as long as the plants are in good condition.
Often I will ask a garden center representative a question I already know the answer to just to test their knowledge.
75% of the garden center staff will give me incorrect information.
Last Spring I saw an employee selling an elderly woman an ornamental non fruiting peach tree and promising her it would grow fruit. I had to intervene.
Just last week I visited a local garden center.... I took this picture of the beautiful giant weeping sequoia they had growing on their front lawn.
So I walked inside and asked the assistant manager if they had any of those Weeping Giant Sequoias in stock.
The assistant manager responded "No. we don't sell those trees."
"Why not?" I asked.
He replied. "They just cannot survive in Utah. You cannot grow them here."
btw... I have 3 Giant Sequoias growing on my property that I planted ... I wanted a weeping one also. **** You can grow them in Utah. The garden center was growing one in their front yard. That's how oblivious garden center staff can be.