To spend $500 and get 1500MQD, you're going to need some sort of unicorn partner ticket, I just don't see it happening. For $500 you're certainly talking about a Y ticket, and at best you're going to get 15%, so you'd need to fly like 25k miles. Or you'd need a discount J ticket going 12500, which I'm also never going to believe you can find for $500.