Twitch Prime regularly costs $79.99cdn/year.
BUT
You can easily follow instructions on Twitch.tv and link your account to your amazon account (Amazon offers a free 30 day trial for prime)!
This means you can make a new Twitch/Amazon account and claim a free month of Amazon/Twitch Prime and claim the 30 days of RS membership for free.
Head on over to:
[url="http://twitch.amazon.com/prime?ref_=sm_w_tup_ln_t_c&redirectRoute=ZGlyZWN0b3J5"]https://twitch.amazo...te=ZGlyZWN0b3J5[/url]
And setup your account.
When done, sign in on Twitch.tv and look at your Twitch Prime offers on the far left side of your screen, redeem your RS membership!
More info:
[url="http://services.runescape.com/m=news/twitch-prime-offer---free-one-month-membership?oldschool=1"]http://services.rune...hip?oldschool=1[/url]
NOTE: This may not be available everywhere but it is definitely available in North America.