So to add to that,
$105 for new keg
$35 for 4" TC set that includes gasket ferrule and cap
$35 for 4" TC cap with two 1/4" NPT welded posts (we'll ignore the PRV, customization, and dip tubes for now).
$30 for 2 ea ball lock adapter sets with 1/4" NPT adapters
= $205
No labor for welding, no dip...