Email list creation and bulk mailing

Need to build an email list for a select niche. Emails will be collected from a website and so you need to be able to effectively get them. Subsequently need to mail to the Email list gathered. Expecting about 50 000 addresses. Please only serious and experienced bidders. Explain your bid based on the first step, which is the list building. Then also how much you would charge per 5000 emails sent.