This is why my mother went out of her way to purchase a costly one that is known to be good quality, (dyson), even if the price is a bit more than the usual. It actually lasted quite a while... until my idiot brother decided to vacuum up some water. >.<;
She's since bought one of those tele-ad ones and... it's actually pretty decent. The suction is great and it works wonders on both carpeting and tiles. Mind you, at the price she bought it for, it had better work wonders. Probably helps that it has a 10 year money-back guarantee - as long as bro doesn't try to vacuum water again. :/
I guess vacuums are one of those things that you pay for quality. A cheap one just won't cut it for long.