I am looking for a book written most likely, but not necessarily, by
Cortazar.  My father read this book in the 70s - 80s, but doesn't
remember the title.  The premise is quite unique though - as you read
the book, you were given instructions to what page (or possible
chapter) to go to next, so you'd go back in forth in the book (but not
directly back to front, like the movie Memento).  When you read it
that way, you got one ending, but if you just read from beginning to
end, you would get a different version.
I think if you came accross this book, you would know what I am
talking about.  My father read the book in Russian; I am looking for
an English version (doubt you could find it in Russian).
The name of the book in English would be satisfactory, a source to buy
it for a reasonable price would be a nice extra.  Also, if you know of
a book with this structure not written by Cortazar, that should work
too, I am just fascinated by the concept.
Thanks!

I believe the book you're looking for is Julio Cortazar's "Hopscotch"
("Rayuela" in its original Spanish text.) Here are some online
descriptions to help you verify that this is the book you want:

"Argentinean writer Julio Cortazar, who died in 1984, is probably best
known for his reality-twisting stories and the 1963 novel Hopscotch, a
masterfully written schizophrenic text (the protagonist seeks to
disassemble his character into a continuum of non-referential moments
and the author suggests an alternate order in which to read the
chapters)."

Eye Weekly
http://www.eye.net/eye/issue/issue_02.22.96/ARTS/bo0222a.htm

"Probably Cortázar's most famous book, Hopscotch has been called
'fiendishly esoteric' by Salman Rushdie. Hopscotch (1966)... A book
river of 700 pages, and 155 chapters, which is given to reading in two
ways, either in a linear way, from chapter 1 to chapter 56, or in the
order given by the author, and which starts from chapter 73, to 1 - 2
- 116 - 3 - 84 - 71 - 5 - 81 - 74... to finish chapter 131."

University of Puget Sound: Pages of Josefa Lago Grańa, Ph.D.
http://www.ups.edu/faculty/jlago/fl380/source5.htm

"Hopscotch ('Rayuela' rolls gently off the tongue, while 'Hopscotch'
realizes the jerky landing on another numbered square) 'consists of
many books, but two books above all'. The book can be read straight
through or by jumping between chapters in either the order Cortázar
has set, or any other the reader wishes to create. Due to its
meandering nature, Hopscotch has been called a Proto-hypertext novel.
It was probably Hopscotch that Cortázar had in mind when he said 'If I
had the technical means to print my own books, I think I would keep on
producing collage-books'."

Cached archive from Trill-Home
http://216.239.33.100/search?q=cache:XX2jwmlH9OUC:www.trill-home.com/cortazar/hopsc.html

Since I had read "Hopscotch" many years ago, the title occurred to me
immediately when I saw your question. This is the search string that I
used in seeking online information about the book:

Google Web Search: "julio cortazar" + "hopscotch"
://www.google.com/search?hl=en&ie=UTF-8&oe=UTF-8&q=%22julio+cortazar%22+hopscotch

AddAll.com, an excellent book search utility, lists several sources
for purchasing "Hopscotch" in its English translation:

AddAll
http://www3.addall.com/New/compare.cgi?dispCurr=USD&id=207311&isbn=0394752848&location=10000&thetime=20030413125309&author=&title=&state=AK

While I was researching your question, I came across this 1973
interview with Julio Cortazar that you may find interesting:

Center for Book Culture
http://www.centerforbookculture.org/interviews/interview_cortazar.html

One piece of recent fiction that resembles "Hopscotch" is Michael
Joyce's hypertext creation entitled "Afternoon: a Story." This may be
purchased online for $19.95:

Eastgate Systems, Inc.
http://www.eastgate.com/catalog/Afternoon.html

If you enjoy "Hopscotch," I suggest that you check out the works of
the great Argentinian writer Jorge Luis Borges, many of which have a
surreal quality which I find similar to Cortazar. You might also enjoy
Vladimir Nabokov's "Pale Fire," which has a very unusual dual-layer
structure.

If "Hopscotch" is not the book you were seeking, if anything I've said
is unclear, or if a link does not function, please request
clarification *before* rating my answer; I'll be glad to offer further
assistance.

Best regards,
pinkfreud

Thanks a lot, pinkfreud for a nearly instant answer!  This is EXACTLY
the information I was looking for.  I will surely check out your other
suggestions.

Thank you very much for the five-star rating and the nice tip! I hope
you will enjoy "Hopscotch" as much as I did. Be sure to set aside a
nice, long period of time in which to savor this unique book.

~Pink