I haven't read the book mentioned, but for an assembler that will run on an Apple, there are at least two now-freely available Apple II assemblers: the S-C assembler, and the Lisa (the name doesn't refer to the pre-Macintosh computer of that name) assembler. Both were commerical products at one time, so both are quite usable. You can download the assemblers and documentation at:
http://www.intergate.ca/personal/gslj/iiefreeware.html
Other popular Apple II assemblers include:
EDASM (the tool kit assembler)
Merlin (Big Mac)
ORCA/M (APW)
You could try eBay or something for these. There are versions of Merlin, ORCA/M and the S-C assembler that can assemble 65816 code also. There were several versions of all 5 assemblers, intended for different machines and operating systems, so you'll have to find one that matches whatever you've got.
It can be convenient to have an assembler that runs on the 6502, rather than using cross-assembler, especially when debugging. Most Apple assemblers were written for 5.25" disks, so finding disks to save your work on could be an adventure.
Good luck.