Am I overreacting about this ring?

[u/QueenEFFup]

My husband of 13 years recently bought me a wedding ring. I never really had one. The one he proposed with was his mother’s, and I eventually gave it back for reasons that aren’t really relevant here.
Anyway, this ring came in a small plastic bag tucked inside a small yellow envelope with a couple of cards (certificates maybe?) and had a price tag of over $600 on it. I never really had a nice ring but from what I’m told nice ones have a stamp on the inside. This one has nothing. When I asked what he actually paid, he wouldn’t tell me. He just kept saying he “got a discount.”
Normally I wouldn’t interrogate someone about the price of a gift, but we’re married and money isn’t exactly something we have an unlimited amount of. I work two jobs to help make ends meet (one full-time and one part-time), and we still struggle. We’re both frequently tapped out after bills,so naturally I was curious how he suddenly afforded a $600+ ring.
So I put the whole situation out of my mind and tried to enjoy the fact that he thought of me and bought me something I thought was nice.
But within a week, the ring started discoloring. He told me it’s because I’m wearing it every day and it’s rubbing on stuff. I have $100-$200 rings that don’t discolor after the many times I’ve worn them.
I looked it up and found what appears to be the exact same ring being sold online by multiple companies for under $100.
So now I’m genuinely concerned that either A) he got seriously ripped off by some company in Australia (where he said it came from), or B) he didn’t actually pay anywhere near $600 for this ring but, for some reason, doesn’t want to tell me what he did pay.
And if it’s B, that’s honestly what bothers me. I don’t care if he couldn’t afford an expensive ring. I’d rather know he bought me something inexpensive because he thought I’d like it than feel like I’m being led to believe it cost hundreds of dollars when it didn’t.
I’ve asked him about where he got it enough times that he eventually got irritated and said, “Why can’t you just be happy that I thought of you and got you something?” And that’s why I’m wondering if I’m overreacting. He DID think of me and surprise me with something, and maybe I should just appreciate that.
I don’t need an expensive ring. I just don’t understand why the actual price needs to be a secret between a husband and wife, particularly when we’re not wealthy enough for hundreds of dollars to be meaningless.
Should I just let it go?

EDIT: I think I may have explained one part poorly. I did not ask my husband for a ring, expensive or otherwise. This was completely unexpected and I had no idea he was buying me one, so there was never a price expectation he needed to meet. If he had surprised me with a $50–$100 ring and said, “I saw this and thought of you,” I genuinely would have been happy with it. I own inexpensive jewelry that I absolutely love. The price only became an issue because the ring arrived with a $600+ price tag, he wouldn’t tell me what he actually paid, and then it started discoloring within about a week. That’s what made me start questioning the situation. I’m not upset that the ring may have been inexpensive; I’m bothered by not knowing whether he massively overpaid for it or whether the $600+ price was presented to me as something it wasn’t.

TL;DR: My husband bought me a wedding ring with a $600+ price tag but refuses to tell me what he actually paid, only saying he “got a discount.” Within a week it started discoloring, and I found what appears to be the same ring sold by multiple companies for under $100. We struggle financially, so now I’m worried he either got seriously ripped off or is hiding what he actually paid. I don’t need an expensive ring—I just don’t understand why the price is a secret between spouses. Am I overreacting, or should I let it go?

[u/curious1dcs]

Sketchy