You mentioned that "the finishing price" is $300-$400 - is that your cost, or what you are going to charge the customer?

What is your profit margin?

You mention a low ad budget - why is that? You can build the cost of advertising/marketing into the COGS.

What is your exact manufacturing cost for the product, including the shipping cost (to you) and if you want to include free shipping to the customer, the the shipping cost to them, and the cost to package it and advertise it? Once you have that, create a reasonable profit margin to give you the actual sale price (allowing for future discounting).

If you truly are in the luxury market, you will not be discounting often (or at all.)

Now that price issues are out of the way - is this something that can be manufactured on demand quickly? Because what if no one wants it - you won't want a whole warehouse full of inventory if the product never sells. That's a nightmare scenario, better to have a minimum amount on hand and have a supply chain that can spin up to replenish stock. Get a good idea of your initial needs via a preorder site like prefundia.