I’ve written extensively about selling domain names to end users, and one thing I want to recommend is that you use the registrant email (or phone number) found in a Whois lookup as a means of getting in touch with the proper person.
Oftentimes, a business website only offers a contact form to contact them. If the company is larger or if it’s a company that would need a customer service contact (ie an ecommerce company where most people are writing to check on orders), your email may be lost in the process or reviewed by someone who doesn’t know how to handle your request.
Instead of taking a chance and sending the email via form that may not be read by a decision maker (or calling the wrong department), use a Whois service like Domaintools and find the email address on record. Chances are good that it’s a person in the executive offices or possibly the actual business owner.
I’ve also found the History tool to be helpful, since many companies change the Registrant email once they grow sufficiently enough that the owner/founder is more hands off. The History tool costs $15/month as part of the Silver membership, and if you are serious about buying domain names and need to check on a domain name’s history, it’s an essential tool.