I’m not sure it’s worth painting to sell. People might want a different colour plus they’re easier for a potential buyer to inspect them.
On a general point about painting wheels...... I realise you are talking alloys, but how does it work when you paint wires ? The 4/4 currently for sale in Surrey has painted wires, they look superficially smart but if you look closely the paint isn't very even. And what is there to stop the paint from clogging the rim/spoke junction ? (Same query regarding powder coating and stove enamelling).
Peter 2009 3-litre Roadster "Ivor", royal ivory / green