I love loose powders; right now I'm using L'Oreal's Hydra Perfect Powder if you're looking for something cheaper (I'm pretty sure it's $10 or less) and it works great. I also used to use a Prescriptives loose powder, I forget what it was called but it worked well too. The only loose powder I haven't liked is Clinique's Blended Loose Powder -- it was kind of oily for a loose powder and I didn't like how it blended.
I haven't tried any high-end loose powders, but I do love Cornsilk Classic Translucent Loose Powder in No Color. It's a very finely milled loose powder that controls oil without looking chalky or cakey. It's like $5 at the drugstore. I like it so much I'm on my 2nd tub