Advice on startup strategy. I WILL NOT PROMOTE

I need some advice on starting this business. Depending on which route I take, cost of goods is between 12 and 30k. I only have about 3k liquid to allocate to this as I am literally going for broke trying to start this business. I am leveraging credit but as this isnt the only business venture I have currently, but I normally dont like to bite off more than I can chew with credit. I am planning on allocating that money towards marketing and seo and running a pre-order campaign to validate my idea in the marketplace and I will have something to base spending that initial large sum of money on. Is this a good idea? Is there anything you would change? Any and all advice is appreciated. I will not promote.