It all depends on where you’ve got it, how good it is, how it’s priced etc., so any answer you get here will be very imprecise. To be honest, 10 a year is probably a good starting point based on what you’ve described. Your direct sales will be very, very slow to non-existent until the product and your company become relatively well known. And the vast majority of boutiquey retailers hardly sell anything- most of them make their money from things like design services, or they go out of business (so don’t offer generous terms).
From first hand experience, if you are planning to go into manufacturing with a specialty product, you want to make sure you’re using production methods that scale well from very low volumes. Nothing that requires big tooling costs, like injection molding. And don’t build a bunch of inventory right out of the gate. It’s better to be out of stock for a few weeks in the unlikely event that it takes off than it is to be stuck with a warehouse full of stuff you can’t sell.