My engagement ring cost £400, my wedding ring £100 and my wedding £3k and would have cost a lot less if we weren't keeping parents happy. (5 years ago)
So I'm totally not one for 20k destination wedding etc and I would have been happier eloping or with a little registry office do, but I was still young enough to bow to parental expectations
But if my DH has got me a £30 ring when he spent more than than on a watch I would have been upset. Not because I want a big expensive thing but because it could mean he valued himself more than me. And I want a relationship where I am treated as an equal.
You only need to spend a few hours on the relationship boards to know it starts with penny pinching when dating and becomes financial abuse when children come along.
And whilst spending £30 on a ring isn't a sure fire way of telling if someone is going to be financially abusive, spending very little on your partner compared to what you spend on yourself, and then being defensive and implying they are money grabbing is a definite red flag
This is the kind of man who will expect his wife to continue to contribute the same amount whilst on maternity leave, and expect her to pay out of her savings.
Who will expect her to pay for everything for the baby because she is a woman. Who will watch her go without new clothes, or haircuts, or any hobbies whilst he swans around with the latest bike, or golf clubs or fancy pants watch.
Then when she wants to return to work she won't be able to because 'childcare is more than her wage' and he won't consider her career prospects, pension contributions or own opinions worthy of consideration.
Then a few years down the line he will bitch and moan that the house is his and the car is his and the money is his, and that means he doesn't need to do any housework, or parenting or take on any of the mental load.
And he will moan that he is the only one bringing in money whilst making it impossible for her to do so.
If she does get a job it will have to fit around school hours, because he won't do any of the lifts, and if the kids are ill he will never take time off because his job is too important.
And when they finally split up and get divorced she will be left scraping by because she's not kept up with her career and he will complain about every penny of child maintenence he pays (if any) and bitch about his crazy ex wife.
Because this is the same old story that happens over and over and over again on this forum and other always starts with a boyfriend whose tight with his cash
So whilst you are right that expensive rings aren't necessary and expensive weddings aren't necessary this isn't really about a ring. it's about an attitude and a relationship.
This could have just have easily been a man who bought himself an expensive watch just before christmas then bought his finance a box of chocolates for Christmas. Or a man who orders steak when the woman is paying on a date but will only let her order salad when he is paying.
The wedding and engagement side of this is a red herring.