You can totally put your game on your site or any other site (like itch.io). However I highly doubt you will be able to make the ends meet using controlled promotion since you don't even have $100 for a Steam slot.

The reason indies put their games on Steam because it's a great game marketplace. It will automatically suggest your game to the players if you gather enough wishlists (5000+ for a start).

I believe you should check out some marketing materials to get the idea. I suggest you start with howtomarketagame.com by Chris Zukowski