Where can I buy replacement home theater speakers?

Hi,

I have an Onkyo 5.1 home theater system. Recently two of the speakers went bad. I need to replace them. I called up Onkyo support but it seems quite costly to buy from them. Is there any store online which might be selling these speakers? I don’t mind buying a different brand but I don’t know how or where do I search for a compatible speaker? Any suggestions of stores would help.

Thanks!

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