Boy, that is a tough choice then, but generally, you get what you pay for. My brother used to be the district manager for S. CA Petco's and he said it varies wildly on the death rates of fish depending on who took care of the fish at each store. Hopefully your buddies are in the good category. I've never had a fish die inside a warranty so I don't really consider it. I just watch the fish for a while before I buy them to make sure they are acting normally, and don't have any Ich or anything.
I'd say go ahead and add some plants.
I know the manager well and he genuinely cares about the department. But he's not there 100% of the time and not all the employees who work in the aquatics dept are as caring as him. Out of the 5 who work it, I'd say 3 of them care. Without going into too much of the details sometimes things happen and now I just try to be more cautious.
I'm probably going to transplant one of the crypts I have in my other tank after I do my next water change this weekend. Any other suggestions on other plants that would work well in my (very low tech/low light setup)?