You will find many musicians reticent to “talk fees”. I recommend you phone around to all your local harpists and ask for their suggestion as to what you should charge. Takes courage but it is worth it.
Once you figure out who is the highest peg your rates there and let the rest know your new rates. The other harpists may raise their rates to match. Brings everybody up a bit.
We have one client who asks for this info yearly.
We are smaller resort style destination.