Transmission ARM no longer free?

Well so far at least there's only been two prolific developers WhoCares? and super-poussin. Without them there'd be little in the way of community add-ons available. A lot of that open source stuff is designed to be installed on say a ubuntu system not a heavily customised Debian system like the ReadyNAS. With community add-ons typically being the work of one developer it's a lot of work.

Now both of the developers have produced add-ons with the option to donate in the past. Unfortunately due to low donation ratios, a small fee needs to be charged. Even so, the devs are giving away a lot of their time.

It's perfectly fine for add-on installers to be sold and both the prolific developers do make it clear that the original source for the software was developed by a third party and that GPL (or similarly licensed) code is used.

If you think you can justify the time and expense to develop some add-ons making them available for free then go for it. Sadly most developers have only developed a few add-ons and come and gone.