how to extend SXR80 (Cost effective)

[ALWAYSaSTUDENT]

I have SXR80 router and 1 satellite. Router at Level 1 and Satellite at Level 2. Now like to enhance week signals at Level 3. Adding a satellite is quick, easy and expensive option. No need of high throughput at Level 3. Would appreciate some cost effective options. 

[plemans]

You can always use just a simple wifi extender. It won't integrate with the network for the orbi usage but does work. 

I've seen a EX2700/3700 (and other higher performance devices) connected to an orbi network just for lower throughput coverage. 

Again, its not going to integrate or have the same (or even close) performance but it should connect