Networking is one of the bread and butter core tasks of your business, as it seems evident when you say everything is "on the cloud".
I would advise to have at least an employe dedicated full time to network/system task besides the consultant, and only let go the consultant after knowledge transfer/that persorn has proved himself/has declared himself confy enough with the role.
Even then, you could mantain the consultant in a less significant budget for more complicated emergencies, or as a contigency plan (could you bring him on board?). I would do without the firewall maintance company on the short term though.
Be aware that firewall maintenance often is just a generic term for keeping up the contract, or at most availability of spare parts, and the software up to date (CheckPoint contracts for instance) , so I would double check if much more is involved on that.
You need someone to take full ownership of the networking and security area, that will keep up with the technology, will procure new solutions, does the interface with vendors and more importantgly yet, will document properly and have a full idea of the present baseline and a planned path for the future.
One persorn that will also start building and maintaing monitoring systems besides the ones your cloud vendors give you, and local servers to streamline network operations, optimize the local network and even having local backups of important projects.
Someone who will will setup secure remote accesses both to your local network and to your remote servers. For instance, here I have setup automatic wifi and VPN provisioning with security built-in for Apple users.
The daily to daily maintenance tasks are an unecessary distraction to other employees too. Often when setting up services, human nature as it is, they will do a rushed job, as it fits them, as it is not clearly neither their core training or they have the ownership of the task to fit it all in the bigger picture.
How much does it cost you every minute you have a network problem or that you are down? Furthemore, how much would it be valuable to have a core of in-house resident expertise? This boils down to much more than a numbers game/cost exercise - this could be a business strategic decision down the lane.
Disclaimer: I am a system/network/security consultant with an ISP background and usually work for large / several thousand users organizations.