Missed a CBS network show - options to watch it via other means?

So we missed the Supergirl finale (yes, a guilty pleasure) because when I transferred my Season Passes to my new Roamio I (sigh) missed one.....

What are my options to view it now? I see CBS has a channel on my Roku - they want $6/mo after 7 day trial - I could start and then cancel. I don't have Hulu (it's not free, right?) I don't mind having to sit through commercials this one time - are there any painless options?

Thanks!
/j