I bought the Dyson purple pet vac about 8 years ago and it works as well now as the day I bought it. There are a few vacs that claim to have the same or better suction than the Dyson, but how well will they work in a few years?
I recently purchased a $39 Bissell Powerforce upright compact vacuum (7 amp) that picks up pet hair & dander like you would not believe. Shockingly better than the hundred dollar 12-13 amp D.Devil model I previously owned. And much quieter too. More money spent does not necessarily mean a cleaner home. (But you also get what you pay for. The power cord is a little shorter than most & the accessory tools are cheap. But if you have a smaller home, it will probably work well for you.)