New connectors typically are low profile surface mount components now, as the excitement is with small high density connectors. These sort of connectors (available in enough styles to make your head spin) can be had from . digikey, mouser or any other professional electronics supplier.
Tricky to use due to needing a package library for your pcb design tool (theyre all different, the small ones at least), and hard to navigate the product t life cycle ( are they gonna stop making them next week, or is it a thriving product line? How do you know?)
Card edge connectors, where pads on the board engage a connector are common, and can be had from any electronics supplier. These are old technology, though, and have been around since the 70s or earlier.