Car Demon has a wide variety of PHP constants that can be used to modify functionality.
Over time many of these constants will be turned into settings that can be adjusted on the settings page. In the meantime you can define these in your wp-config.php file right above where it says:
/* That's all, stop editing! Happy blogging. */
CD_PRICE_GAP if defined the price drop down will create options between the price start and price stop in groups made up of the gap. For example, if the price starts a 0 and stops at 10000 and the GAP is defined as 1000 then it will create the following options to select:
0 – 1,000
To do this you would add the following to your wp-config.php file:
define( 'CD_PRICE_GAP', '10000' );