If you add users too fast you will get put on 30 day suspension by Twitter. To find and add the users you want, you'll be lucky to do that at more than 100-200 per day in the beginning. Hence the timescale. I can do it, but your budget is way too low There will also be some monthly fees although not large. If you are still reading this and if you want it done right by a professional, let me know.
Terence.