I find that the crack that ive bought has often had a higher amount of cocaine in it, than the powder usually does. But there's really no difference if you were say shooting pure cocaine powder, or injecting crack with the same amount of cocaine.
And crack is not really cheaper, but you can get it in smaller quantities, whereas the smallest amount of cocaine you can get is usually two times as expensive, and I've only been able to obtain dime bags of cocaine a few times