Number 2: The time factor. Think about if you have ever grown anything from seed. Especially something that is not an annual (a plant that only lives for about a year from germination). A perennial (a plant that lives for more than 2 years) grows slower, each species has their own propagation method, soil and moisture needs, some can grow from seed, some do better from cuttings, it’s a tedious process, but once you get them growing, you have to keep them alive until they are a reasonable size. Sometimes this means growing the plant on for more than a year, the longer you grow it on, the bigger the plant. The bigger the plant, the more it costs to keep it alive, ergo, you want to buy a pretty big shrub in flower. It costs more because it took more time to grow said plant. Don’t even get me started on trees.
So see, plants aren’t that expensive if you take into consideration the time associated with growing them to reach a size that you would want to buy them at.
You trade your money for time and it saves you the trouble of nursing seeds into shrubs.
So next time Linda comes at you with her ridiculous notion that you spend too much money on plants, educate her, and be honest about those pumps.