You don't need to go to a trainer. I learned everything I know from reading, watching videos and having my form critiqued. It's actually better to go to a good powerlifting gym and make friends with some strong people, but you don't NEED to. At least not until you get to pretty elite levels.
In fact, going to a the typical trainer at the gym is a waste of money, effort, and is MORE likely to get you hurt (like rhabdomyolysis for instance). Half of those guys will just have you balance on a bosu ball while doing some arbitrary movement, and rake in your hundred+ dollars an hour. You might go home more sore than a 30 minute lifting session, but you effectively wasted your time, and probably simply decreased the likelyhood you'll even go back.
No, lifting weights isn't some magical or super technical thing (unless you are doing Olympic lifting, then, then I'd suggest getting a coach, not a trainer).
Edit: FWIW, if you can find a trainer that can DL 500lbs that is at a regular gym, I'd be liable to eat my hat. Now show me that same trainer that actually trains his clients with a routine for beginners as good or better than Starting Strength, and I'll eat my hat without ketchup.