Sure, if I'm bored of it after ~1 month I'm at a loss.
If I'm not however and can endure it for 3 months, I'm not.
Since I've been using the same 3 since (1)BC-(2)WotlK-(3)Legion I'd have a net gain of several hundreds of $€.
The quality of armor would rise, because Blizzard wants to sell that stuff and I would most likely buy another 5-10 sets for 40€ each. But that would still be *way* cheaper than 10-13€ a month.