how much is a IG handle really worth?

I mean a good word

like

"racing"

obviously its worth whatever someone wants to pay for it, but are words like that worth anything unless you can find a specific buyer?

Some people would be interested in the username and some other focus more on the acc

As @majdi107 said, you can add a spin to the username and you will contain the keyword you are targeting + something else. If your content it's top-notch, trust me, the people will remember your username even if it's not something high "IG handle"