KP,
I have been polishing my aluminum, and leaving it raw. That way it can be touched up more easily every so often. I figure once you clear coat it, then to fix it, it would have to be stripped and re-polished. I do have a Caswell polishing wheel, but its such a dirty job, I have been sending mine to the chrome shop for polishing.
Eastwood makes a rattle can clear that I have experimented with.
http://www.eastwood.com/diamond-clear-gloss-set.html I have not used this on any restorations because I am just worried about the durability.
Once again, I leave it raw and touch it up. I use metal gloss polish for the touch up, you can also use their sealer as a protective coating.
http://www.metalgloss.com/. This metal gloss stuff is FANTASTIC, it really works well to clean up old chrome and take the bluing off of exhaust pipes as well.
Also, some of my production parts for Kewlmetal are finished to match the OEM brushed aluminum. They are powder coated clear. I think this is a nice option for the durability. I will find out from my powder coat shop how they are doing the brushed look. But for powder coat, I have the Eastwood gun in my garage. They are selling the gun for $69 !
http://www.eastwood.com/hotcoat-powder-coating/powder-coat-guns/original-hotcoat-powdercoating-gun.htmlI have a toaster oven for small parts, and I recently added a full size oven in my shop. I love having the powder coating capability at home and I use it a lot.
Matt