Hello,
My partner and I are accredited and verified developers of steam trade bots (we can show examples, and prove verification from reddit and other clients), and jackpot sites. We can create exactly what you are asking for. We have a unique winner picking system that we can implement as well. Our bots are faulty proof, and our admin panel makes it VERY EASY to change settings, resend trades, and collect tax. Its slick, and has all the functionality that you would require to properly admin and run the jackpot. We would include the basic front-end that we can customize, create the bot, and the admin panel. We will also set up your domain, secure your server, and include extensive documentation on how to properly run your jackpot!
If you have any questions please feel free to message me here!