Need advice on IPhone purchase

I was planning to buy IPhone 15 from USA, rate of IPhone 15 128gb in Texas is 499$ whereas in Florida it's 780$. People been to USA please suggest is this common in USA Is this common in USA where rates differ from state to state? Price in India is close to ₹63000 /724$ on Amazon India. I'm confused how IPhone price same as in USA . I need suggestion shall I buy from USA or India. PS: It's my relative who is getting an IPhone for me.