SSD capacity vs speed

I have a question. Out of the multitude of manufacturers offering solid state drives now, I've seen the prices, as well as the capacity of each drive, run the gamut of cheap to ridiculous. My question is...for the drives that are on the cheaper side but have more storage: are you getting a drive that will be more prone to failure versus something more expensive? How are they able to sell an SSD with say, 1TB of space, for less than another brand that sells something like a 250GB model for...

SSD capacity vs speed