Roadrunner, I have purchased things with my costco card, and had them mailed to people directly (gifts for family). The same if they needed to return something they can do it either in the store or via return label. So I'm assuming Costco is fine with this sort of thing.
When the kids were in diapers it was really worth it to have Costco membership for their diapers and diaper wipes.
I signed up for a Costco membership when my computer was killed by a lightning strike and had it replaced. For me Costco is not cost effective, because I shop more. I do feel like the things I purchased were of value (everything from a sink faucet combo for a kitchen remodel, swim goggles and speedo suits for kids, some clothes for me, replacement vacumn cleaner) but I just feel like I bought more stuff than I usually do, even for food. I was able to get a bunch of photos developed and some protein powder for a family member.
My favorite things (the things I will miss) are their kirkland organic olive oil, their rainforest unground coffee, their large but inexpensive wine selection, prewashed salad selections, spanokopita, and their rotisserie chickens which my kids loved. I'm not a fan of almost everything being the higher grade more expensive version, and the large amounts needing to be purchased. I can do better grocery shopping if I alternate between Harris Teeter focusing on their sale products (and to get their meat) and Food Lion for everything else.
Admittedly it's been 15 years since I've been in Aldi but from my last experience you couldn't pay me to shop there. They would keep discounting food items (meat and deli items) that were literally discolored and rotten but still for sale, saw mouse droppings and even a live mouse running along an aisle.