Any engineers around St Louis that could tell me if a wall in my house is load bearing. Preferably for less than the $3-400 I've been quoted so far?

You can't really tell if a wall is load-bearing unless it's obvious, e.g. long ceiling spans with an obvious "droop" leading to the wall. I had one that looked load-bearing until we removed the drywall and found it wasn't touching the ceiling.

Also, I don't know any engineers who would charge less. It's a risky game being a PE and homeowners/residential contractors are the ones who sue their engineer. All of my PE friends quit working with homeowners.

Does it run perpendicular or parallel to your rafters?  Do you have rafters or pre-fab trusses?  If you're planning to remove a wall and put in a beam I'd call a contractor and let them worry about the engineering