thats where i get my paint supplies here in GA..They do a pretty decent job making the color.But still off a little(depending on color/metallic)
Im pretty sure they only sell by quarts? Maybe smaller,dought it tho.
for a new bumper,scuff it with a gray or red scotch brite pad.make sure theres no shiny spots.Clean it with an ammonia based cleaner.scuff it some more.
Clean it with the ammonia based,then wax and grease remover.
Tack it off with tack rag and spray the color.suggest spraying sealer down 1st,but base coat will be ok,just might take an extra coat or 2 to cover.especially if its white or silver.