Buy elvolving ring 3 or not?

I recently wanted to test gms again and I found 300m on my mercedes and I dont know what to spend it on. I was thinking of buying an elvolving ring (nr3) since thats the only ring Im missing out of those 3, is it worth buying or is there any better rings to obtain for less cost? The rings are like 145m in galicia if Im not mistaken.