Nessus is still a thing? I thought it died along with my highschool days... but I guess I've never had the urge to spend over a grand to use a piece of software for a year.
Anyway, if you really want to use a scanner,
Nexpose and Metasploit are both owned / distributed by Rapid7, and they both have free versions for single IP users. (with limited functionality in the case of Nexpose)
I think OpenVas is still kicking around, and Qualys also exists. I agree with Phage that these scanners are gonna light up the network like a fucking christmas tree but hey.
Or if paid products are your thing, you could go get Core Impact, sure it's like buying a car, but they did pivot attacks first mang.