MUF is nothing but silica. Don't waste your money. It's a total rip off. I bought bloody OUNCES of silica microspheres - amongst many other base powders - for next to nothing, and mix myself many kinds of powders at home, including a primer, setting powder, finishing powder, color corrector, etc. I haven't actually bought a face powder in a very LONG time. Nothing I can find in the stores, including MAC, MUF, or anything else, does near a good a job as my own mixtures.
Get to TKB or Coastal Scents and take a look at the 'filler' powders there. That's what you are looking for. If you're not sure, just email them. They will help you make a choice.
FYI NOTHING will keep your face completely oil free all day. Not even silica microspheres, believe me. I say that as a person with oily/combo skin. Get some of those blue face blotters from Clean & Clear or a generic brand - they're exactly the same as the name brand - and make sure you PRESS your finishing powder into your face with one of those thin, round sponges after applying foundation. That helps a great deal more than just dusting it on with a brush.
And Halo is a nice product, but it definitely does NOT keep your face oil-free all day. Not in your wildest dreams will that happen.....