Goal: to get spoken (and written) fluency with a limited
vocabulary, in a short time. Most 4-5-year young children,
around the world are fluent with a small vocabulary, no matter
which language they are speaking. Most of them don't know
what the word "grammar" means.
If you must use a book:
Do not use a grammar.
Easy to find:
"Esperanto Learning and Using the International Language",
by David Richardson. About $15.00.
I just saw in Amazon:
"Esperanto (Teach Yourself)"
"16 Used from $61.57, 4 New from $185.16"
This is ridiculous. It should be about $15.00.
I like this book better than the first one, but not at those prices.
"Gerda Malaperis" (original name: "Dialogoj"), was written
to learn Esperanto, but it requires a teacher to explain the
grammar. I prefer this book to be read after completing
a course.
If you could use computers:
My original post had 5 links, but right now they allow me only 2.
The simplest course for rapid fluency is "La Zagreba Metodo".
You can buy it as a book + a sound-cassette.
There are several versions in the web, both text and sound.
Like a book:
Interactive:
Interactive, many languages:
La Zagreba Metodo:
http://esperantofre.com/zagreb/zagmetod.htm
To learn Esperanto: http://esperantofre.com/edu/lernia.htm
Look well at the whole page. Among other things, it has links
to applications that will help you to write in Esperanto.
Enrique