Why do you need center caps ? Surprising though, every place I have seen them for sale they came with center caps..
To me it's just one more part to keep track of when pulling a flat on the trail or pop a bead back in or whatever.
boosted inline 6 50. trim turbo
40" super swamper boggers
high pinion d44 front trussed
ford 8.8 rear axle conversion
se 9500 milemarker winch
locked front and rear
rough country steering stabilizers
clayton long arm
3inch body lift
2 coil spacer lift
eagle alloys 15's
on-board air system
kc daylighters 100w long range
Do your stock center caps fit? If they do, you can just paint those. Did you try the junkyard? See if you can find a 15 inch wheel with a center cap at the junkyard, and take center caps from it. Otherwise, my best advice is either the internet, a Mr.Tire or similiar large franchise that deals exclusivley with wheels/tires, or just paint your hub and forget em.
mine have seen alot of highway use, off road, and many a hoses' to em, and they hold up just as good as anything else. also they are kinda flexable if you run em into something. And hey, if one does break... eat some toast.