Is it worth $75, probably if it is in good shape. Is it a good buy probably not unless all you have to spend is $75. The "Flex-drive" system is like a weed-eater shaft where there is a flexible square shaft the drives the blade. The flexibility allows the blade to be tilted while still remaining attached to the "flex-cable". Replacement parts are hard to come by, and the flex-shaft requires a fair bit of maintenance.
Buy the best tool you can afford, and buy it only once. Buy cheap and you'll buy again
BTW, welcome to the site. Please drop by the Who We Are forum and give us all a little introduction to who you are and what you do...we don't bite
MTCW,
Dave