cool idea, I don't think it would be very functional. but cool idea. You'd need to be able to adjust it on the fly & get it up & out of the way for mowing the rest of the lawn for one. 2nd issue is keeping your angle of attack with the edger perfect from on the mower would be difficult. If you got off track or turned a bit you be bouncing the blade off the concrete & mounted to a heavy mower it won't just bounce up (like it would in your hands) it will keep hitting & either wear out or break the blade, break the edger shaft, or chip up the concrete. I see issues with this. There was a guy I saw had a weed eater mounted in a similar fashion.... cool but not very practical.
The thing I hope is, once you get your feet wet by inventing a product, you can then fine tune it and make it better and better. I think there is a need for a product that does this job the best it can.
It might be neat if it could some how be mounted to maybe a spring device that would allow for some give when driving. I don't know for sure, but I would think somehow it should be possible to have a guide that would roll along and get it on track?
could be a good idea, i guess it makes sense for only really long commercial lawns because it isn't going to be precise. Also the only problem i have with this is that if your drive and and you hit a bump, your line wil probably cut short, and therefore the rest of your trimming is not going to trim off everything. you can also see the positive side to this too: if the grass is well leveled then you will be able to cut evenly all along the edge.
Price wise this is wayyyyyyy to expensive. For half that price you can find some clamps, wood, and make it yourself.