Most any domain can be looked up via a Whois search. A quick lookup of the site domain and then the domain of his vtc.net email address.. turn out to be in Arizona and there are phone numbers attached.
Truly paranoid types can also call Directory Assistance to verify he has a phone number, the Arizona Secretary of State to verify he has a business license and perhaps the Arizona Better Business Bureau to see if there are a rash of unresolved complaints.
MC/Visa transactions are generally safe as any problems are easily rectified with the credit card company.
Following the
http://www.gsrenterprises.com/ link (his parent company?) from his site however takes you down a path that looks less than professional... Myself... I'd recommend from a business standpoint that he break the unprofessional looking relationship between his locksmith business and the UFOs and Sexy Starletts.