Abebooks.com or ThriftBooks often have older editions of Addison Wesley Science 10 for under $15 + shipping. Older editions (2002–2006) are 90% similar to newer ones – only the climate change data may be outdated.
Science 10 Addison Wesley textbook is a core resource developed by Pearson Canada Science 10 Addison Wesley Textbook Pdf
Platforms like Scribd often have student-uploaded versions, though these may require a subscription. Abebooks