Cheap longbow may not be the way to learn about them. The cheaper longbows may be difficult to shoot and some will have handshock that will cripple your elbow.
Try and find someone in your area that could let you shoot one before you buy.
There are also different style longbows, R/D, D shape, and three piece hybrids.
You can pick up a used one for little more than half price if you look hard enough.
Go to Tradgang.com and check out the classifieds.
John