Hi
Is the less expensive book worth getting or does it cover the same ground as the book that Carson helped co-write that is much larger please?
The handbook does not overlap, it explains the method.
If you are interested in theoretical matters and you have the time to read it properly, I can recommend it.
I took Beale's class last spring where we worked through the handbook. It's a really valuable exercise but it is very time consuming. If you have the time and access to all the secondary sources needed to do the research for each passage the handbook is well worth it. If you want the insights gleaned from the process at the major instances of NT use of the OT go with the commentary.
The introduction to the commentary outlines the basic process included in the handbook.
Bottom Line: Having used both with Dr. Beale I recommend the commentary to anyone who asks unless they are sure the handbook is what they need.
I can't speak to the Handbook, but I use the Carson/Beale commentary every week in my exegetical work for sermon preparation: it is a great resource, and one that really helps me in understanding the text.