If you're looking for an item in the middle of the price range, why not consider this Marc Jacobs Cross Body Bag. While the price is very reasonable, this piece is an easy wardrobe update. You might also want to check out this Anya Hindmarch Crossbody. It's an attractive option both price and quality-wise.
If you're gonna splurge, then you absolutely must check out this Valentino Crossbody. This piece seems pricey, but it's well worth it.