Suitsupply's new navy Copenhagen fit jacket is a pretty good basic unstructured cotton casual type deal. I'd prefer patch pockets but that's my only issue with it. £199 on the UK site, so probably about $300 from the US one.
For true style beginners Reddit's malefashionadvice board is pretty decent
They'll basically tell you to wear button-down shirts, cardigans, dark denim jeans and Clarks...