So, for those interested, here is what it costs me personally to wash with soapnuts....
FYI I don't have a scale, unfortunately, so I can't say for sure how many ounces 22 soapnuts comes to!
I wash every day (except for the weekends), with the 22 soapnuts recipe:
-22 soapnuts (which Tina said is 100g [Thanks Tina!], which is approx. 3.5 oz.) makes 8 oz finished liquid
-I use roughly 1 oz. of finished liquid per wash
so, 3.5 oz. unused soapnuts makes 8 washes for me, and 3.5 oz. soapnuts at roughly $1 per ounce = $3.50, so divided into 8 washes = $.43 per wash
Since I wash every day (except for the weekends, so 20 days per month), that comes to $.43 per wash x 20 washes = $8.60 per month. However, some folks can re-use soapnuts effectively one time, getting double the amount, so then the cost per month is $4.30. A lot of people don't wash every day though, so they can save more money that way too. Also, I don't need to use conditioner, so there's that savings there too!
ETA 8/1/09: After almost a year now of soapnut washing, I've started to use just a half ounce per washing (every day still). Also the Cellande Midlands soapnuts are very powerful, so I only use about half of the amount of soapnuts in the recipe. So my cost is now just approx. $2.15 a month! (without the lime/lemon included)