In the past I have had dealer paint grill only to have it flake off in a few years.
I would look into replacing its has better results, easier to do and may be close to same cost. On my WK I have not I replaced chrome side moldings with black. want to do grill and rear molding also.
2015 WK II 5.7 Overland, Offroad Group II,- 2008 WK Limited 3.0 CRD, - 2003 WJ Laredo 4.7, - 2001 WJ Laredo 4.0, - 1999 WJ Limited 4.7-