Painting anodized aluminum window frames

I want to paint dark anodized aluminum frames, factory baked on finish to a white color. I have been told by the manufacturer / installer that they need to be sanded, primed, and spray oil painted. Cost is $2300 for 11 windows, high due to the protection required for spray painting. Is it necessary to go this route, or possible to brush paint or some other simpler way.
We want it to last.

 

This is a painting question, not a window question, so perhaps the moderators will move your post to where the professional painters hang out.

In addition to any advice given here, you could go to a professional paint store (not big box)- someplace like Sherwin Williams, Pittsburgh Paints, Benjamin Moore, etc... and ask what they would recommend. The biggest concern is adhesion- as mentioned sanding and priming may be advisable because of an extremely glossy baked-on finish. If the finish is not extremely glossy, and is more of a matte finish, the preparation may be altogether different- and not as extensive. I'd suggest you remove a window part as a sample (a sash or something similar) as an example when you go into the paint store for advice.

But paint stores may be able to recommend specific products that could reduce the amount of preparation needed.

 

Genarally aluminum windows can be painted with either latex or oil. The surface needs to be clean!! and not too glossy

If you paint them with latex you should add emulsa bond to the first coat of paint. Oil base shouldn't need an additive to adhere. Both latex and oil can be brushed but a spray coat will look better. Another advantage of spraying is a thinner film of paint [especially with oil base] This means the coating will have less effect on the movement of the window. Oil base enamels will dry to a harder finish than latex will.