I just sat through a webinar by Macmillan, here is a list of textbook options. The bookstore already has used copies at $150+ without any of the online add-ons. Look around, but buying one or another ebook and/or printable looseleaf version looks to be the least costly route. If so, there's no need to rush to buy the text in advance of the start of classes.
Macmillan Krugman & Wells Macro takes you to the textbook page and HERE jumps you to the Macmillan student bookstore page. They try to upsell, with various packages as per below. These packages do however appear to add value, unlike the add-ons I examined a few years back.
- just the Looseleaf which gives you an eBook version that you can print, at 5¢ a page that's cheaper than buying the physical book, esp as the first few chapters are a review of Micro
- the LaunchPad option includes an eBook. LaunchPad looks quite useful, consider adding it
- the slightly more expensive FlipIt + Launchpad + Looseleaf Sheets adds videos and other pre-class material that is well done. not a costly upgrade
- Sapling is a fairly sophisticated homework/quiz function. I think you can purchase after-the-fact, again, I'll update once I've checked with the bookstore as I don't want to mandate something after you've bought other components.
Amazon appears to be more expensive than any of the above options, and what they sell in general will not include access codes to LaunchPad / FlipIt / Sapling. However you may be able to find a used 3rd edition. I've not been able to find a Table of Contents online to confirm, but typically changes are modest (updated graphs, examples but no wholesale changes to content and order or presentation). If you find a ToC, email it to me and I'll confirm whether the old edition is adequate.