Bug: After playing around for a while with the script I've discovered that the "fletch for x minutes" setting actually buys x number of supplies and fletches them, then sells them to the g.e. and buys back x number of supplies and continues. This is exactly what I wanted the script for, however I believe this was meant to be achieved by a different setting option.
Another bug: the fletch until x level setting attempts to buy all the supplies in one go, problematic if you want to go for 99 as if you cant afford all the supplies at once it will sit there pressing +5% over and over and attempting to buy when you don't have the money.
TL;DR for people wanting to continuously fletch without risking a large sum of money on the account which may be banned, set the bot to "fletch for x minutes" and enter in 2000 or so, this will buy about an hours worth of supplies at a time and sell back to the g.e. and buy more when it runs out.