I use Amazon Web Services for free. They will give you free EC2 instance of Ubuntu or Windows Server with 1GB memory and 1 cpu. Technically it's only free for a month but I have been on it for 4 months now and haven't been charged.
The trick is to not store too much media so your bandwidth utilization is minimal.
The catch is you need a credit card with atleadt $1 or $2 dollars on it, in order to create the account. They don't charge you but they want a card on file.
The trick is to purchase a $5 or $10 pre_paid credit card to use. Mix with semi anonymous gmail credentials if you really don't want to be billed. Maybe use a tor exit node if your really cautious. Experiment with installing and configuring to your hearts content knowing that the most you will be charged is $5 or $10.
With AWS it's easy to open and close ports, backup, have multiple free-tier servers up. Create a server in less than a minute. Run the Flarum install script and bingo. Easy ssh access with key file.
Drawbacks are that everytime you shutdown the instance, (don't see why you would need to) you will receive a new ip address. No domain name. However, being that flarum is not out of beta there is no reason to run it on a production site. For these reasons I feel AWS is the perfect $2 dev environment. (Technically it's free if you have a credit card and want to monitor your bandwidth usage / cost. To be smart though, it's best to use a prepaid cc so you can control any unforseen bills.)
