The Brother TN-430 has 3,0000 pages worth of toner.
In general, the Brother TN430 does not use much toner when compared to other printers. You have to make sure that you are not printing on high quality settings all the time, otherwise, the printer will run out of toner faster than normal.
There are no other options for new OEM Brother TN430 toner cartridges on the market. You can get one refilled by an ink shop or by looking for certified refilled cartridges from places like Costco.