Instead of playing a guessing game, your best bet is to ask around locally, take a picture with you if you don't have the part. Even then it's a guessing game...

Every state/every city/every town has different pricing and different products used. What someone pays in California won't be the same in Illinois or Florida or N Carolina.
While you can gauge an idea, if cost is really a factor, a stock car might be the best option...

OR

If you are handy in some autobody, or have unlimited data, surf YouTube and learn some things. It is not hard to paint.. let me repeat that, it.....is....not....hard...to...paint... especially something that small.

Any and most auto paint shops will provide a spray can if you supply the paint code, and they ll also supply clear coat for you... a couple of sheets of sandpaper (220 and higher grit) you ll have it done sooner then a shop can do it.