speaking of which... without being a bit more specific you will hardly get the answer
would you like to send spam? buy a database
would you like to scrap specific website? do general mining and selling addresses?
with adequate budget you can hire a freelance coder - easy to find
general purpose software is cheaper but results will be poor especially if the other side fights back and has some level of protection
are you looking to harvest from domain/forum or just scarp from specfic pages? if those pages include patterns at end and start e-mails , you can try this tool to filter @ from bulk of text Text Mechanic – Text Manipulation Tools
alternatively linux is good for this
wget -q -r -l 5 -O - http://emails.com/scrap.html | grep -E -o "\b[a-zA-Z0-9.-]+@[a-zA-Z0-9.-]+\.[a-zA-Z0-9.-]+\b"
but for harvesting it's better to hire programmer .