I think the term you might be trying for is "crossmember".
My answer must be... "it depends". If you really like that car, and if it's priced significantly lower than other similar cars for sale near you, and if the bend isn't very bad, then take it for a careful test drive. Drive it STRAIGHT AHEAD through a puddle of water and examine the wet tire tracks leading from the puddle - you should see only two wet tire tracks, where the rear wheels exactly followed the front wheels. If you see four, then the car is "crab walking" or the bend was significant enough to change something else in the car's geometry.
But... there may be other hidden damage, too. A crossmember isn't an easy thing to bend, it would have taken a pretty hard impact.
Ultimately... that car is a gamble. If the price is low enough for you to take the risk, and if you can afford to replace it if it turns out to be really problematic, then go ahead & buy it. If you're short on money, though, or if the car's price is about the same as other undamaged cars near you, then walk away from this one.