As already mentioned in an above post, the Plymouth Walmart has a few SnowJoe 21' roof rakes selling for 75% off at $9.00, and it is a good quality aluminum handle with a plastic scoop. Not as sturdy as the all aluminum scoops but should last a long time with reasonable care.
Another use for a 21' long roof rake is to use it for trimming tree branches while standing on the ground.
Check out the Corona razor tooth 21" hand pruning saw for $42.29. It cuts on the pull stroke which works pretty good screwed/attached to a 21' long handle.
Trimming pine tree branches is very easy fast work, while trimming oak trees take a lot more effort.
Is not a bad idea to wear a helmet and safety goggles. You can actually trim through a 6" diameter oak limb with this set-up in about 30-minutes ...... and you will believe it when you actually do it!