It depends on what your goal in attending the conference is. If you're interested in learning from others in the industry, the I would say that $150 is pretty inexpensive for all the content you're going to get.
If your goal is to network and talk with vendors and catch the keynotes, then you'd probably be good with the exhibit hall only.
I think each option has its place. Personally, I think that for the extra $125, you're getting an awful lot (considering that you get breakfast and lunch both days too), but it's your call.