At the same place where you buy most stuff: the Grand Exchange.
Buy them.
from the ge
You don't. You have to buy it.
yes from the grand exchange
Yes, you have to be a member to have a home in Runescape.
just buy at GRAND EXCHANGE
there are many different sorts, look at this link
To make a rune crossbow you need 69 fletching. Use a knife on some yew logs to make a yew stock. Then use rune crossbow limbs (you can buy them or make them if you have 91 smithing) on the yew stock. You'll then get a Runite c'bow (u). Then use crossbow string (you can make it by using sinew on a spinning wheel if you have 10 crafting or just buy it) on the Runite c'bow (u) and you'll get a rune crossbow.
Sorry you do lose it but you can buy another one
I am not sure were u can buy it at a shop but u can buy both cheap at the Grand Exchange.
You can either buy them from the Grand Exchange, or there is a place in the wilderness where there are a bunch on the ground.
you can buy the from beefy bob. (he is located on the road between Varrok and Lumbridge)