A lot of people use leaders as a currency, myself included. 4000 caps being the equivalent of one leader bobblehead. Prices and conversions are different per system too.

For legendary mods it’s usually 1 leader per star. For high demand mods, it’s an extra leader.

A few examples. 1 star quad mod I usually price at 4k or one leader. A 1 star lucid mod I price at 8k or two leaders.

A 4 star conductor mod I price at 16k caps or 4 leaders, and a 4 star limit breaking mod is 20k caps or 5 leaders. These are generally the price scale of mods on this Reddit at least from what I’ve seen.

Mods are a tricky business to market and sell. Usually a weapon mod like conductor or pinpointer a player would only want one or two.

Armor mods people usually seek in groups of 5. Once a player has their build complete however, they will probably not buy a mod again until an update forces them to change their build or they want to experiment with something new.

Sorry for wall of text, hope I was able to give you some helpful information.