Scrape box to find opportunities : how many proxies to start?

I just bought Scrapebox and discovered I need proxies to make it work (hidden costs : yeah :D )

I found a tutorial where the author advises a 25 proxies to start (smell like affiliation…)

From your experience : is it too much or exact ? (I want to know if I must absolutely spend 50 USD in proxies to fuel Scrape box).