You can SRT effectively with a RADS or YoYo system with a rope, a Grigri or even better an I'D, a handled ascender, and some cordage for foot loops.
While there are more efficient ways to climb than the RADS, i.e. requires less energy expenditure in the climbing effort, you will eventually reach a point where you need to do up and downs or in and outs, and at that point you'll need a device that allows you to move up and down the rope without constantly switching gear. The RADS provides about the most cost effective way of doing that.
A Pantin is not required, a chest ascender is not required, and a chest harness to hold and advance the chest ascender is not required. So if getting started at minimum cost is primary, the RADS is a good way to go, probably the only thing you'll need is the GriGri or I'D and some 7-8mm cord for foot loops. Be aware if you go the I'D route, which I believe is far better, it comes in two sizes. Be sure you get the size to fit your rope.
The GriGri is spec'd for 11mm rope max. but I know a lot of people use it with 1/2" rope. I can't speak to the wisdom of that because they've been doing it for a long time. Although, I have heard of a GriGri slipping and I can't help but wonder if the over size rope interferes with the design of the GriGri.
Even with all the gear I have, and all the techniques I have experimented with, I find the RADS to be as useful as any, less equipment intense, and extremely simple to go up and down on.