it depends on the quality of the weights b/c i got a cheap plastic 160lbs weight set with a barbell that holds...160lbs. It was 29.99 on sale at Sears. Theres nothing wrong with it except the barbell is sorta weak(can only hold 160 lbs).
If you are really serious about lifting, get a good bar. Ivanko and Texas Power Bar are two good brands that are reasonablied priced. By reasonable, I mean in the $150-$200 range. Weight plates are important, but a good bar can last your whole life.