When I began as a pastor in 1981 I had one-and-a-half shelves of books in my little home office. I had not been to seminary so I didn't have the collection of books that a seminary grad would have accumulated. Most of the books I did have were popular Christian books, nothing that allowed me any in-depth study that would be helpful in ministry.
I began to go to a nearby college library to find books that would be helpful in sermon preparation. To my surprise, I found other ministers there as well. However, as a bivocational pastor it wasn't always convenient to depend on the library being open nor did they always have the resource material I might need for a particular sermon or study. I needed to build up my own private library, and I did. Today, my study is lined with bookshelves around three walls all filled with books.
About a year after beginning my pastoral ministry I enrolled in a Bible school. The required books for my classes were helpful additions to my library. Some of them were found at an off-campus used Christian bookstore at very reasonable prices. I find that some seminary students are not interested in keeping their textbooks which become for sale at similar bookstores. If you live near a seminary or Bible college you should always check out to see if a used Christian bookstore is nearby. You can get some really good deals there.
Our local library has a Friends of the Library book sale each fall. For ten dollars you can become a member of this organization which allows you to purchase books at this sale a day before it opens to the general public. I found some great buys at this annual sale. My favorite story out of this sale is that I bought the two volume Theological Wordbook of the Old Testament for $2.00 one year. It retails for around $100.00.
While I have bought hundreds of new books from Christian and secular bookstores, I have also found some great buys at Goodwill, yard sales, and auctions. Most of my recent purchases have been used books through amazon.com. Sometimes you have no choice but to purchase a new book, but when you can buy some used ones as well it helps the average!
I have also volunteered to review new releases for one publisher. I got that book free plus the publisher sent me another new book for my trouble. I got to select the free book from a list the publisher sent me. I didn't do this very often, and I'm not sure the publisher still does it, but it was a way to add more resources at no cost.
One last thing I did was to ask my bivocational church to give me a book allowance. Part of my salary package was a $400.00 a year allowance to buy books and other resources. That's less than $8.00 a week, but it does allow the pastor to add to his or her library with no out-of-pocket expense, and because it's an allowance it's not taxable. BTW - I always spent more than my $400.00!
Of course, there are now computer libraries that can be purchased for far less than one would spend for books. While they do include some excellent resources, some of their material is dated and not as helpful. Still, it can be a very good way for ministers to build up their resources. I've owned a couple of these, but I have to admit that I prefer holding a book in my hands.
I'm the same way about e-books. I have a number of books on my Kindle and NOOK devices, but I prefer to use these for general reading and not research and study. I also question the pricing of these e-books. As an author I'm glad that the cost of these e-books is not much less than the price of the book, but as a consumer it seems to me they should be much less expensive.
Building a library can be very expensive, but it's something that every minister must do if he or she wants to be effective. As I talk with bivocational ministers many of them say they just don't have the funds to build a good library. However, as you can see, there are many ways to do so without spending a lot of money. What you do spend must be seen as an investment and not an expense. You are investing in God's call on your life and on the people you have been called to serve.