You may be able to reduce your manufacturing cost by considering these factors.

1. Size and quantity of PCBs.

The cost of a PCB is determined mainly by the overall area. A more compact layout will reduce your cost.

2. Board material

Use standard FR-4 board material with 0.062" thickness and 1 oz copper weight.  Choosing non-standard materials may increase board cost and delivery time.

alt Choosing non-standard manufacturing settings may increase board cost and delivery time.

See also: Low cost PCB prototypes.