Wedi is much lighter and easier to cut/shape than backer board. depends on what you want it for- table top, plaque, etc, but Im partial to the ease and cleanliness of wedi. It would be worth the drive, grab plenty. :)

Wedi board is expensive and I heard you have to seal it thoroughly as it disintegrates if it gets wet. Don't know if this is true. I know nothing about it from experience.