Well, I am not what I would classify as a "trainer" but I apprenticed with one and have started several horses under saddle. I am currently doing so w/my 2 yr old gelding. If you can't afford a trainer, what you're doing is a great first step. Teach him to lead, tie, pick up feet, load, bathe, everything he needs to know on the ground. How do you lunge? Do you know about "join up"? Disengage his hindquarters, introduce him to every potentially scary thing you can find, toss ropes all over his body, find a large piece of wood for him to walk over, introduce him to cars(running and off). Take a plastic grocery bag and tie it to the end of a short lunge whip if you have it, and slowly introduce it to him. The goal is to be able to rub it all over his body w/out him spooking at the noise. Don't go too fast though, first just "clear the air" around him and gradually get closer.
Once he has all that, start introducing him to the saddle blanket. Let him smell it, lip it, and rub it all over him. If he doesn't spook toss it on his back and take it off several time, from both sides. Yes you mount from the left, but everything you do to one side you must do to the other.

After this it gets tricky, it all depends on the way he reacts to all of these new things. Once you get to this point message me.If you have any questions message me and I can try to walk you thru it. Good Luck!