A selection of companies providing broadcast or bulk email list management solutions and their pricing at 1000 emails per month:
iContact – $11.90 per month*
Emma – $30 per month
ConstantContact – $30 per month
CoolerEmail – $39.95 per month
eROI – (contact them for a quote)*
PHPlist – (free, but only for experienced techy types)*
Note that these are just the ones I’ve come across, and this doesn’t include setup fees. The starred products are systems I am currently managing for my clients.