You can buy OEM replacements that are already color matched from the dealer/online but some of the colors show discontinued.
McGeorge Toyota, an online OEM parts center, lists them at $229.95 + shipping for the assembly.
Exterior Trim - Lift Gate for 2003 Toyota 4Runner | Toyota Parts
76801-35410-A0 - white pearl
76801-35380-B0 - Silver
76801-35410-B0 - black
76801-35410-B1 - dark grey - Discontinued
76801-35410-F0 - champagne - Discontinued
76801-35410-J0 - dark blue - Discontinued
76801-35410-J1 - greyish-blue - Discontinued
So depending on what you want to spend, your best bet might be to remove it, sand and then paint whatever color you want.
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2003 4Runner Limited 4wd V8 - Build thread on Tacoma World
FJ tcase swap, VVT intake swap, Solid Offroad motor mounts, Doug Thorley y-pipe, Bold Performance cat-back, ADS shocks F&R, Metal Tech LTHD springs rear, 1" body lift, 285/75/17 Toyo R/T Trails on Sequoia rims, Coastal front bumper, CAD rear bumper