You might do well at £450, but I don't think you're a million miles away.
I recently sold an immaculate set of MV2s with similar tyres for £400. When it comes to OE rims like these the demand seems to go up and down. One point you can have 3 or 4 people looking for a set of 107, and the next 3 for sale.
If I were you personally I'd aim for £450 and go no lower, but I tend to like to sell things quickly. If you're happy waiting just leave them at £500 and ride it out. They'll go eventually