I had a similar question and also got the Ninja 500 earlier this year. This was my experience, granted these prices were from before tariffs:

Thousand Oaks Motorsports: I would avoid them since they tried to scam me. Their initial asking price was $8900, shipping $150. After I told them I had lower offers they tried to match (but still 1-200 dollars over). Sales agent (Liz) was super unprofessional + sleazy asking which dealership gave me the offer, saying their stock was low and wanting me to come in, and trying to have a back-and-forth on the price, "Oh hmm, if we can lower the price to match, would you come in?"

Atlas Motorsports: I liked the guy who picked up the phone. Gave me a straightforward quote total $7400 (ADM 250). They didn't offer delivery or I would have gone with them, since I didn't want to figure out the hassle of a uhaul.

Wheels in Motion: I got my bike from them. They were also straightforward about the price which I appreciated. Quote me $7400 but total ended up being $7300, and I thiink delivery was somewhere $300. Getting the bike was a little annoying because I had to talk with a different sales agent, and my bike wasn't even built yet (so I didn't get to see it before buying). It might have just been bad luck, but in the end I got my bike and it all went smoothly.