What you really want is a HEPA filter. HEPA filters remove dust particles that are a fraction of a micron in diameter. You will have very clean air in your room with one, and you have to dust much less often.
The best part is that you can get one for less than $100. IMO, Honeywell makes some of the best ones that are widely available. Go to a home center and a mass retailer (e.g., Home Depot, Target, Wal-Mart), and see what they have available. If your room is small, you can get a smaller unit for even less money.
Finally, if you want an ionizer, you can get a small one at Wal-Mart for about $15. I used to use a small one in my 2000 sq ft home, and it would fill the house with ozone within a couple days. Some comments about ionizers: They do 2 main things: They create ozone, which freshens the air and has mild antibacterial qualities; and they put an electical charge on dust particles that makes the dust stick to surfaces (so it's not floating in the air). The drawbacks regarding ionizers are that you need to air your room out frequently when using one, because too much ozone is bad for your lungs; and, the electrical charge causes dust to stick to your walls and baseboards, making them get dirty quicker.
My personal favorite combo is the HEPA filter and a separate small ionizer. Relatively inexpensive and effective. If you have a room less than 150 ft sq, you can use a small HEPA filter, costing as little as $40. Look on Amazon.com for user ratings and reviews to find the highest-rated ones.
P.S. To answer the other part of your question, no, the Ionic Pro doesn't work well at all. Consumer Reports said they sucked and were a fraud, and the Sharper Image sued C.R. over the article, and lost in court, and now Sharper Image is going out of business. The reason the ionic pro doesn't work well is because it doesn't really circulate the air (no fan), and there's no filter, so there's nothing to catch the dust. This means you have no real filtration, and the dust sticks to your walls and floors. Ionic Pros are really nothing but big ionizers. A small one is more than enough for a bedroom (be sure to air the room out a few times a week if you use one). You can get a small ionizer at W-M or Home Depot.