It can be significantly cheaper, depending on the season you intend to travel.
If you can't get a flight to Bali, or if it is too expensive for you, you can look into the option to book a flight to Jakarta and then take a domestic flight on the same day to Bali.
Airlines such as Citilink, Batik Air, Air Asia, Lion Air, and Garuda are flying to Bali several times a day. Ticket price one way: 50-150USD.
If you choose to travel to Jakarta first, tt's good to at least have 3 or 4h difference between your arrival in Jakarta and the next flight to Bali. Because you would have to go through immigration, pick up your luggage and then go to the terminal for to catch your domestic flight.