Have you checked out the Contemporary section on tPF?
And you don't even have to go designer or contemporary, some high street stores also offer nice bags but I would keep away from designer copy cat or trendy styles. Not saying this is your style but I have a plain black washed-leather All Saints bag I bought in the sale for £100 (approx. $150). It's gives of an urban vibe like Rick Owens. I get as many compliments on that bag as any other and it's still going strong years later. What I'm trying to say is don't compromise just because you think your budget is low, actually $500 can buy you something in your style and can last years.
You should check out Madewell and Zara. I know they're predominantly clothing stores but I really like their selection of bags as well. The quality is great and IMO sometimes better than the contemporary handbag brands.
I like Coach and Dooney & Bourke. I don't have any Kate Spades but my daughter likes them. Michael Kors, Ralph Lauren, Brahmin are also good choices. There's lots to choose from in this price point, so I would narrow down if you want leather, canvas, etc and a style that you love or would use the most. Then you'll have loads of fun choosing your next bag :)