saves budget in bare PCB procurement
1. Try to make your board size as small as possible
2. Use HASL LF instead of ENIG
3. Make 3-4 purchases a year, so each time you can order a larger quantity to get a better price.
4. Choose a thinner plate thickness if you don't actually need 1.6mm thick. Such as 1.0mm or 1.2mm are also commonly used.