The total cost of the GOP plan, as laid out in the working draft linked below, is $713 billion – significantly less than the Obama administration's $800 billion-plus plan. The majority of the alternate plan, $430 billion, comes in the form of tax cuts. Republicans have criticised the Obama administration's plan as too reliant on spending.
This morning, McCain said "we're a long way away" from agreement on the plan. The president, by contrast, describes the differences between Republicans and Democrats as "very modest."
Senate Democrats need at least some GOP support since they are slightly shy of the 60 votes they would need to override a Republican filibuster.
UPDATE: The complete text of the stimulus bill is now available on the Senate Finance Committee site. Read it here> (PDF), if you have some time -- it presently clocks in at 736 pages. (This document combines the packages approved by both the Finance and Appropriations Committees.)