While a lot is going to be made of the fact that the Senate bill's price tag for expanding coverage is smaller than the House's ($848 billion vs $1,052 billion), this does not even begin to tell the full story. The Senate bill is cheaper simply because it does less. It covers many fewer people, and for less time. The Senate bill is not a good bargain.
On a per uninsured person gaining coverage per year basis, the House bill is a substantially better value. The House plan is 12% more cost effective. Over the next ten years, the House bill expands the number of people who will have coverage in a given year, and does so for an extra year, so the number of person-years of coverage expands by 226 million [PDF warning]. On the other hand, the Senate bill starts its coverage expansion one year later, and covers fewer people each year. It will only expand coverage an a per person per year basis by 161 million [PDF].
The House bill is spending, on average, roughly $4,650 per year per individual who gains health insurance. The Senate bill is spending 12% more. It costs roughly $5,270 per year per individual to expand coverage under the Senate bill.
The Senate bill's price tag maybe smaller, but that should not fool anyone. Its cheaper price tag is simply due to the fact that it helps fewer people, helps them for less time, and gives them less help obtaining affordable health insurance. The House bill is a much better bargain, and provides much more health insurance per dollar. When looked at in this light, the Senate bill is clearly the fiscally irresposible way to expand health insurance.