How much for a dress?

I know this question varies greatly, but I’m lost on what is a reasonable number I should set my price point at when I go dress shopping. My wedding is December 2025, so I should be getting to the shopping as soon as possible from what I hear. I have a decent savings, so I technically could afford a designer dress, but never in my life have I considered buying an item of clothing that cost more than a few hundred dollars, let alone a few thousand! Is there like a general rule of thumb to set your dress budget based on your overall budget? For reference, how much did your dress cost plus alterations? I’ve heard alterations can run anywhere from a few hundred dollars to almost a thousand dollars.