My classroom favourites for teaching Greek have long been Athenaze (Oxford UP) and Learn to Read Greek (Yale UP). They both come in several volumes and thus are not the cheapest; but their length is due to the number of resources they make available. (Plenty of good, author-written readings in Athenaze, large amounts of annotated original Greek readings in LTRG. 

However, if you want to use the book just for yourself (rather than to teach a group of students with varying strengths and interests), the one-volume Introduction to Attic Greek by Mastronarde may be the way to go, especially for someone who already knows Sanskrit and thus is already familiar with most of the grammatical categories and concepts we find in Greek. It also comes with its own supplementary website: http://atticgreek.org.

There are various others - if none of the above sound good, let me know what you are looking for and I'll be happy to talk more about what else is out there.

All the best,

    Antonia