1. 2 X VPS 850GB (solidseo vps)
2. Proxies Dedicated 100 minimum (mexela)
3. HREFER (free with xrumer)
4. XEVIL (Free with XRUMER)
5. PI (GSA Platform ID)
1 Take your keyword list, use that as the wordlist in HREFER, have that on a vps
2 export the full current footprint list (too long to explain but) use this to create a GSA filter in HREFER
3 Scrape with your dedicated proxies in HREFER, fine tune it but I do about 3 to 5 threads per proxy so you can get 50m results per day niche specific
4 PI running on the giant vps, use PI to create automation chain from HREFER export to first dedupe (against existing files else you waste so many cycles) then after dedupe copy to new folder for PI to parse, be sure to use the blacklist feature, within a couple of weeks of running you will have an amazing list maker
I do this many many times at larger scale and, well it works very well.
New twist, turn your vps into your own DBC by using CB host file redirect method (thanks loopline) and a further mod with XVIL emulating another service to get that xrumer power in CB (send all the really hard captcha to XEVIL)
Or just buy some shitty spammed out list.