I am curious how many quotes for a custom piece is average? I have emailed/spoke with a few vendors/ designers and am waiting to hear back. This is most likely going to be my forever setting (not stone ) so I want to make sure it's perfect.
I don't know if you are going to get the answer to this as it probably varies widely. If you know who you want to go with and the quote is reasonable that's only one quote you need. If you don't know who you want to go with you need to narrow it down because it will be too confusing to get a lot of quotes that are from very different artists.
Meaning do you have the style you are looking for narrowed down? Because that will help you choose the vendor you want to work with as they all have different strengths and different visions. So I would choose a vendor or 2 or 3 whose creations you love and then get quotes from them and see how that goes.
Do you have the stone in hand? Because that will affect who you can work with as well as not all vendors will work with your stone.