i was looking into something similar, actually a wagon attachment for my lawn tractor with a fan to suck the leaves from the discharge and blow them into the wagon.
However, i found that if i just mulched the leaves as they fell (mulching every couple of days) that i didn't need to rake. and FYI, i have a LOT of leaves to take care of in the fall. Try to get them before they get rained on, otherwise they clump and don't mulch well.
We've had two BillyGoats over the past 25 years and loved both of them. Great on dry leaves, but not so good on wet. You can set the vac hood to different heigths according to the ground type or how deep the leaves are. It can also be used to vac driveways and parking areas. Our neighbor used his BillyGoat on his used car lot and on his lawn. Since we moved a few years ago we don't have trees so we gifted our BillyGoat to my mother-in-law and she loves keeping her yard clean and some of her neighbor's yards, too. Make sure you get the collection bag with the hard plastic bottom. The cloth type bottom bags will get wet and hard to empty.