The IKEA APPLARO outdoor line is pretty great. You can buy as many sections as you want to create a custom sectional outdoor sofa. It’s made from real wood, so it needs some care and to be covered for bad weather (they sell a cover for $60 for it too) but wood is also easy to refresh if it gets weathered (sand it, re-stain with an $8 jar of stain, and seal). The cushions also have removable covers that are washable. They don’t tie to the sofa so I ended up buying heavy-duty self-adhesive Velcro and attaching a small piece to the bottom of each seat cushion and the other side to the wooden seat to keep them from sliding around when sitting. Yes it’s annoying to assemble but it’s very affordable for the size and customizable configurations, and there are other outdoor pieces in the line that match (table, bench, etc.) More on reddit.com

What is the sectional made of, wicker, aluminum, etc? Are their cushions, if so are they Sunbrella fabric? Are the cushions thick or thin? Is their a warranty on said sectional? More on reddit.com

in my experience the fabric is thicker quality but not necessarily more stain resistant. I have a few sets and pieces in a lighter brown fabric and they staining is the same in my experience. More on reddit.com

Double the price sounds really expensive when costco is known for standing by the warranty of the products they sell. The memory foam is most likely a very thin piece on top of the cushion. Costco sells outdoor furniture covers for under $100, those built in covers from outer seem pretty gimmicky. They offer no protection to the wicker frame and the sides of the cushions are still exposed. Also keep in mind wicker wrapped frames are a hassle to clean and below them are the perfect home for spiders and insects. Sunbrella is just a brand that uses acrylic and has spent a lot on marketing and advertising their product. Acrylic is great at water repellency but olefin tends to be more durable and softer. A competitor Phifertex makes better outdoor upholstery than Sunbrella IMHO, but I have no problem owning a set with Sunbrella because they have a 5 year warranty. I just purchased an outdoor set with sunbrella fabric from costco and 2 of the oversized aluminum frame pieces arrived damaged and one of the bolts stripped assembling a side table. Called the manufacturer and they are sending out replacements, no questions asked. If I run into more issues I can always count on Costco or as a last resort, return the set to a costco warehouse even though I purchased online. The Home Depot, Lowe's and all the other big box retailers do not carry the same quality of furniture, their biggest concern is price when selecting manufacturers. Sam's club would be an exception, they also have decent stuff. Whatever you get, if the frame is metal make sure it is aluminum, steel will eventually rust. More on reddit.com