I like ESX. I like Linux. It is absurdly easy to configure Linux as an NFS server and mount it in ESXIi).
I currently use Ubuntu Server for my home lab, but the process is basically the same for Red Hat and derivatives.
sudo apt-get install nfs-common sudo apt-get install nfs-kernel-server
Next, configure NFS so it can server your local LAN. Normally you would list only specific servers, but, well, we're being cheap and dirty today. Open /etc/exports in VI or your editor of choice./etc/exports
Go to Configuration -> Storage -> Add Storage.
Fill in the info, see screenshot.
Wait a minute. Voila! New datastore.
Images to come shortly.