The general store offers Old School RuneScape fletchers the option to powertrain their fletching in the general store itself and even make a profit. This old school RuneScape guide will elaborate on this method.
When looking to dump items into or otherwise access the general store, bring a stack of coins and a fletching knife. Look for stacks of the following items in the store; Oak log and willow logs.
Oak logs, when over 30 in a stack, buy for six coins each. At level 20-24 fletching, these can be made into oak shortbows (u) and sold back for five coins each, a loss of one coin each. At level 25 fletching, Oak Longbow (u) sells for eight coins each, a net gain of two coins per bow fletched.
Level 35 fletching is needed to make willow shortbows. Willow logs buy 12 coins each when over 40 in stock. Willow shortbows sell for 10 coins each and willow longbows 16 coins each. Although there is a loss of two coins per shortbow, it is better than paying 15+ coins per willow log from other RuneScape players.
RuneScape players deciding to use the store to "unnote" the logs get two coins per oak log and four coins per willow log. They lose logs to shop despawning as well as to other RuneScape players. Using a shop in a remote location also means stocking the shop, an additional 30 logs plus logs to replace despawning. It is more efficient to fletch in the bank and take stacks of notes to the general store.
RuneScape fletching guides main link hub page.