I'd rather give money to a fan who's probably a broke student or an artist that could use the support than a cash-cow company, to be honest. Not taking jabs at Nintendo but if fans are the only place I'd be able to get merch for specific IPs from, I wouldn't lose any sleep over them not getting my cash.As much as Wario merchandise is cool, I wouldn't recommend buying anything fan made. It gives people the (somewhat mistaken) impression that it's okay to sell fan art and works, despite none of the money going to the original company or creators. It also gives the impression that stuff on Etsy and similar sites is more legitimate than fan fiction, fan games or fan movies, all of which would be seen as somewhat dodgy to be selling.
But that's just my opinion.