In my opinion, they are pretty overpriced for them. Reason why is cause they are soulbound on use, I suggest that they should only be account bound.
Another way to make them (worth their price)better, instead of making them gather the same amount of times as regular gathering tools, make them gather only once for the same amount as you would as when you gather them normally. For example; when gathering a vein, you hit the vein 3 times for 3 ores, make it that you hit the vein 1 time for 3 ores. This would make it save bag space and a bit of time.