You're making a fundamental mistake. Probably just inexperience. Never, ever discuss cycling related purchases with a spouse. Serious error.Every £20 I spend on the bike costs us £50.
I buy a new crankset for £20 and she retaliates with a shrub in a tub costing £30.
A good friend of mine was considering a new bike. His wife had agreed the purchase. He happened to let slip how much I'd spent on my new bike. He's not getting a new bike.
So here's a tactic for you. You already own a nice phone which would cost £xxxx to replace. You can buy a very nice Wahoo for £yyyy which is shock proof, withstands being dropped, safer to use, crashes etc. comes with a purpose designed mount etc. and is often replaced free if there's a problem. Why not get one to avoid risking the phone?
An alternative tactic is to say nothing when your wife joins a very expensive leisure club. Mrs P did this.......fair play means I can legitimately spend +/- £1000 pa without guilt or recriminations!
Plants in pots are probably a good deal.