Starting to manage 1000 accounts at once will be pretty damn hard and before you know anything yours accounts will start getting banned one after another.
Start small, 200 accounts this month, 400 next month and so on.
You can buy PVA accounts on SMSPVA for $0.50 each -
Code:
http://www.smspva.com/store-new.html
Or if you want to save more money and better longevity of the accounts, buy non-pva accounts from SMSPVA for $0.20/piece and phone verify them once asked to verify for $0.15/account from SMSPVA, that's $0.35 per account.
So, 1000 accounts will be $350, proxies from http://www.blackhatworld.com/members/russian-racket.214646/ or http://www.blackhatworld.com/seo/proxymillion-private-twitter-insta-yelp-yt-fb-google-baidu-whatever-proxies-0-19.809929/unread will be cheap. Make sure to have a monetizing method in hand before pulling the trigger.