Foam grips are usually about 60 g (ESI Chunky), not worth the faff IMO – they have too many disadvantages.
ESI, half lock ons etc aren’t really foam grips are they, these are foam grips (and 15g, and IME don’t slip. Ritchey ones were about 33g on my scales. I found they migrated in allong the bars, but never slipped even in the pissing rain, solved by either a dab of glue or cut an old grip in half and put it between the grip and shifter.
http://www.evanscycles.com/products/bontrager/race-xxx-lite-foam-grips-ec032856
OK that’s without end caps, but the ritchey (and any other bit of plastic/cork) end caps are a lot lighter than the over engineered expanding bolt ODI ones. The ODI end caps probably weigh more than foram grips!
If you’ve not used foam grips since the horrible ones arround in the 90’s. Try them now, I’ve had them on all my bikes for the last few years and won’t ever be going back.