It seems that youre getting a wide variety of advice ranging from going with reissues of the audiophile labels to cheap stuff from Goodwill. The problem is that you need to learn what you like and dont like in classical music. Thats daunting task for most people new to classical. My most salient advice is to use your local library to explore the genre before spending a dime. With the help of a good guide, you can try before you buy. Definitely preferable to spending 30 bucks a pop for reissues.
Speaking of guides, Im not familiar with NPR book but with only 350 pieces covered, it seems limited. I highly recommend the Morins 1100+ page book titled Classical Music, the essential listening companion. It covers the major works of about 500 composers everything from Gregorian chant to Philip Glass. For each composer covered, they start with a short biography followed by the reviews. They always start with the symphonies and then walk through to end with chamber music. For each piece, they review multiple recordings and make recommendations and more importantly, tell you why they made the recommendation. For Mahlers second for instance, they compare approximately 20 recordings.
Im using they to describe the writing because the book is really a compilation of input from the 4 dozen or so contributors that was edited by Morin. They all seem like an accomplished bunch which includes Harold C. Schonberg one of the best known music critics around. Again, I cant recommend this book highly enough. I have two copies one for home and another for the office. Added bonus, its cheap - Only 20 bucks on Amazon.