I want to make our internet connection available to another house about 100 metres away - with direct line-of-sight.

Too far for standard wifi to work reliably (even if it worked on the drive, I don't think it would do so inside).

I am well aware that various pairs of devices are available which can do the job. Do you have any recommendations? Least expensive that will do the job without being rubbish.

Doesn't need any fancy facilities at all. I have a wifi router I can use inside. So this is just for the house-to-house link.