Thanks again! It could definetely be interesting to work with you, but I've recently switched to Godot, I'm not sure you're ready to actually come to the dark side ;)
I think you have the right mindset with you're weapon cycling system. The big problem right now that I see is that you can easily just shoot at a wall and make it so that you get the weapon you want. Maybe mixing the purchasing system with the shooting system could be an interesting way to prevent that? If you shoot, you loose money? And then you have 1 base gun that doesn't cost anything, just in case.
I like the idea of the power for each weapon, I think it could add a lot to the gameplay. I'm still just not sure if it would go well with the cycling weapon system. I think the game would need to have more enemies and different type of movement to be able to really test it out and see if it's fun or not. That's kinda the hard part with prototyping a game sometime, you don't really know if something is actually fun before trying to make it :P
I'd be open to discuss more about it, you can join my Discord or join my stream on Twitch tomorrow or later this week!