Often, quality books on Service Design, Innovation or Design in general can be pretty expensive.
So here are two ways for you to read such books when you are in a moment where money is an issue:
Use your local library
Yeah, old school I know, but most libraries have a good selection of books and many allow you to request books from other libraries.
Use the Everand app

Everand is an app that I've used to read a lot of books. It's like a Netflix for books. You pay a monthly or yearly subscription and can read as many books as you want from their library.
You don't find all the books in there, but for example, you can find a few very good books like:
- The Service Organization
- Service Design for Business
- Change by Design
- Good Services
- Value Proposition Design
- Business Model Generation
At the time of writing, it costs about 12 bucks for a one-year subscription. This means that if I read two books ebooks, it's already worth it.