I've learned so much from Youtube and tutorials where people take the time to do something for free so it was important to me to give away some of my work for the same reasons.
Just played your latest update - it's very very cool. Really enjoyed it and it was fun for me to see my models in your game. Drop me a message if you'd like to collaborate on some more assets for your project. I was working on a little casual plane game a while back and I'm going to be uploading all the assets over time to here but if you need any specific let me know