Wise move to cancel. We get inquiries of this sort all of the time, always from Australians. Travel frauds seem to be very popular there. Lately, most have been of the Malaysian scratchie ticket variety, but there are still plenty along these lines.
Any unsolicited offer with prices much too good to be true is going to be a scam, and you should stick to Australian travel agents rather than ever contract with a foreign company unless you can first vet it thoroughly.
This company is virtually a blank slate. The contact information gives only an address, which is probably inaccurate, since it doesn't match the address as given by the site registrant when the website was set up. I also question why they want payment in US dollars, since that is neither your currency nor theirs.
The reason you can't find anything about this so-called travel agency is that the WHOIS information for the site tells me that it's only 9 months old. The site IP address traces to the US, but the site registrant, who has the suspicious name of ***** *****, is supposedly located in Playa del Carmen at an address other than the address on the website, which says the business is located in Cancun. You can find the site registration information by going to www.domaintools.com and lookiing up the WHOIS for traveltomex.com.
Mexico is a very high scam country. They do have a national consumer protection agency named Profeco. You could contact them to see if they are legitimate. But I doubt they are, as they conform to the scam pattern.