Pricing a magic item.

[Jakonen]

Fog Sight Lenses

Allows normal sight in non-magical fog/mist/smoke. In addition, reduces concealment miss chance by one level to targets in smoke/mist/fog/similar. (50% - 20%, 20%- 0%). Concelament granted by darkness, or spells like blur still function normally.

Now how much does this thing cost? I made it on a whim, mid session to avoid having to roll for a sneak attacking enemy rogue, but now they've mugged the guy for the lenses and wonder how much it costs.

[Bob Bob Bob]

Step 1: Start with with a similar magic item. Since you made a weaker version of this... 6,000 gp? 4,000 gp? It's just whatever the GM thinks is reasonable. It's entirely an educated guess based on where you think it would be balanced. The ideal is "cheap enough specific builds might want it" but not "cheap enough all players will buy it".

[Jakonen]

Well being the GM i get to decide what's reasonable... 4,500 sounds good enough.