I quote them both a higher price. Since a wealthier client wants my time, my time is worth more, so I can afford to increase my prices. This may price-out the other potential client, which is my way of choosing the wealthier client. This increases my take-home, while also reducing my workload. The poor client can find a different, cheaper, less glorious contractor to work for them. Perhaps I can recommend them one of my lesser colleagues, as a courtesy.