Even if you're going to drop $3500 or so on a couch with your own damned money, broadcasting it to social media—while at the same time you're running a GoFundMe for a cancer-stricken family member's needs—is utterly tone-deaf.
If she wanted advice about that brand of couch, there are ways to ask that don't make it look like you're just about to buy one: " Our couch is falling apart, so we're going to have to break down and buy a new one soon. I like the look of this one. Does anybody know anything about this brand, or have any others you'd like to recommend that are comfy for big folx?"
That phrasing establishes a legitimate need for a couch, as well as pushing the actual purchase decently far into the future.
I get that the couch she was looking at was on sale—but shit's always going on sale, so it's not like this would be her only chance at it. And maybe she's trying to get a sponsorship deal in exchange for a couch—which is what Anna O'Brien/glitterandlazers more than likely did. (Why not go ask Anna how much she likes her couch, Corissa? LOL.) But making room for your detractors to speculate that you'll be misusing donated funds to buy it isn't a good way to go about that.