Forum Moderators: open
To reach them via advertising you could use specialist trade magazines like CTO and others (in the UK). And trade directories like VNU's. There may be a way you can partner with the big distributors like Computer2000 to avail of their customer database. (They won't rent you the list but they could send an email out on your behalf if they take on your products). There are also associations and professional bodies whom you may be able to persuade to let you speak at a conference. Post or sticky me the product type and I may have other ideas.