Another business segment overwhelmed by marketing vs actual product performance. And where curiously, destination marketing works well.
The eureka boss models and several hoover windtunnel models top the objective ratings, have superior suction, and meet your price criteria. We use the hoovers as they come self propelled, but its been my experience in having bought four and returning two that the quality of this maytag subsidiaries product has followed maytag down the drain. Hence I'd recommend the Eureka.
I'd point out that most of the expensive vacuums like kirby, dyson and oreck always end up in the middle of the ratings pack at best, but that'd probably start a fight. Oops. They're good vacuums, well made, will do a good job. But I dont think you're getting a good value for your dollar.
Claims of "Never loses suction!", like "made with lump crabmeat!" need further analysis as to the quality of the original suction (and predominance of crab meat).
Be equally cautious of the various subjective "comparison tests". The primary one being to throw dirt on the floor, vacuum with your old tired vacuum and then again with a new one. Emptying your old vacuum and re-suctioning will probably get a bunch of extra stuff up, and getting a new model of your old vacuum will probably also produce pretty good results.
Lastly, I love bagless too but the bag vacuums have better suction and emissions than most of the bagless ones. I found a cheap source of bags and bought 3 years worth for $25.
Amazon.com: Eureka 5902BVZ The Boss Upright Vacuum: Home & Garden
Amazon.com: Eureka 4870GZ Boss Smart-Vac Upright Vacuum: Kitchen & Housewares
Amazon.com: Hoover U5725-960 TurboPower 6500 Windtunnel Bagless Upright Vacuum: Home & Garden
This is the one we have (well, two of them...one for upstairs and one for downstairs). Only vac my wife will let me buy. The carpet/floor button tends to break off after 2 years, not recommended for fine hardwood floors as the self propel is very vigorous and may spin the wheels and scratch the floor, and if you adjust the height too low the self propel belt may break when it and the brush belt become overloaded trying to both move the vacuum and grind the cleaning brush into the carpet.
But once you get the carpet height right and keep it off the hardwood, its an effortless vacuum experience.
Amazon.com: Hoover U6616-900 WindTunnel Self Propelled Bagless Upright: Office Products
I'll also put in a good word for refurbished vacuums. Buy from a reputable source like the factory or amazon. I've gotten a refurb from Overstock and it was also good, but have heard that people have had trouble with receiving clearly well used vacuums from overstock. Most of the refurbs i've bought over the years from Fry's, amazon or factory direct appeared and operated as new.
This one is also a reasonable contender, its made using older generation Dyson technology if you're all hot and bothered about that. The primary difference as I understand it from a friend who is an expert in these things (yeah, and he finds computer stuff equally boring) is that the tip of the suction/cyclone nozzles is a little different and if you dont empty the cannister when you're supposed to and overfill it, the unit may lose suction quicker than the newer design. Hey! I thought these things didnt lose suction!
Hoover Mach3 Cyclonic Upright Bagless Vacuum - Wal-Mart
The Mach 5 has also been very well recommended and is a clone of more recent dyson technology, and the bissell healthy home is also often given thumbs up by the pro's as perhaps an even better version of 'dyson' technology. But the bissell is a little over your price range.
Amazon.com: Bissell 5770 Healthy Home Bagless Upright Vacuum: Office Products