My local library had all the Harrington on Hold'em books and a number of other poker books as well. You could ask the librarian for an inter-library loan. I'm sure some library around you has it.
If not, ebay has some pretty cheap
Here's the whole set for just over the cost of one:
http://cgi.ebay.com/Harrington-on-Holdem-Three-Volume-Set-Great-Deal_W0QQitemZ230347102125QQcmdZViewItemQQptZUS_No nfiction_Book?hash=item35a1c1d7ad&_trksid=p3286.c0 .m14&_trkparms=65%3A12|66%3A2|39%3A1|72%3A1205|240 %3A1318|301%3A1|293%3A1|294%3A50