This is not a DIY item, but looks like a pretty nice digital saxophone for ~$500:
Yamaha YDS120 Electronic Saxophone – NAMM 2023
https://www.sweetwater.com/store/detail/YDS120--yamaha-yds-120-digital-saxophone
I am hoping-assuming-guessing that it can be used as a midi controller, as well as with the built in synthesizer-sample player.