Take stuff from your last job
I don’t mean that you should steal office supplies but a good bootstrapper takes what they can from the resources that they have. The things you can take from your job ethically include your contacts and relationships, knowledge, and other things you can buy cheap. Employers have to get rid of things like that old laptop that you have been using. You can offer to buy back products you have been using from them at very low prices and they may be perfectly happy to do so.