Flat Face wheels, right? Find an autobody shop that will strip them using media (crushed walnut shells is popular for this purpose) they can paint them easily if they have a set up that spins the wheels and they should be able to use a DuPont paint or equivalent, Wurth is fine if you plan to use a spray can, but the pros have similar silver paint that comes in bulk - then they should put on two coats of clearcoat.
$125 per wheel would be tops so yes you are looking at $400 or more for that kind of job. DIY and see how it turns out, maybe $75 for materials and the rest sweat labor. Do NOT use sand blast. Bead blast maybe but sand is too coarse for this.

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'95 E320 Wagon my favorite road car. '99 E300D wolf in sheeps body, '87 300D Sportline suspension, '79 300TD w/ 617.952 engine at 367,750 and counting!