I have a BNIB Ruger LCP (.380) and may consider letting it go.  Not sure what the going rate is, any suggestions? 

I'd set my asking price for a cash sale to be the lower end of what's available brand new from an FFL.

 

Most places are listing it in the $270 - $300 range on GunWatcher.   Palmetto State Armory is selling new (OD Green model) for $249.99.

 

http://palmettostatearmory.com/index.php/firearms/ruger-lcp-380acp-od-green-03706.html

 

After (reasonable) transfer fees and NICS, that's $291 - $341 for a brand new one (although some of those have lasers on them as well).

I sold a lightly used one with a laser on it for $275

They improved the trigger in 2013, so whether you have the old or new trigger might make a difference:

 

edit: trying to add a link, but my computer won't let me for some reason.