Hi Anonymous,
Your question is a tricky one. Some costs are relatively easy to estimate and are available by consulting your local UNICEF office. They should be able to supply you with a list of the available drugs, therapeutic milks, RUTF, ReSoMal and some other supplies you may need. You might also consider consulting your national essential drugs list for hospitals to see if the drugs are available.
Regarding the other costs it depends much on the size of your SC, where you intend to establish it (at what level of health facility) and in which country context. It also depends on whether it is an emergency, stable setting and whether you have good case finding in the community.
I think perhaps you should consult other NGO's who may have already set up stabilisation centre's in your area. The names of NGOs should be available from UNICEF, the Nutrition Cluster or (if neither of these is present) the Ministry of Health.
Some countries also produce operational guidelines which will give you a better indication of the operational requirements for inpatient and outpatient settings.
Depending on context you may need to consider other associated potentially high costs such as ambulance transport, food for caregivers, security among others.
FANTA guidance in handout 5.1 is also generic and a little outdated in some aspects see:
http://www.fantaproject.org/sites/default/files/resources/CMAM_Training_Mod5_ENGLISH_Nov2008.pdf
The following guidelines may be more informative but remember they are country specific, see:
http://www.cmamforum.org/Pool/Resources/India-Operational-guidelines-facility-based-management-SAM-2011.pdf
As a final thought you may want to consider looking at the coverage of your outpatient programme before deciding how many SCs to set up. Putting resources into expanding outpatient treatment and investing in community mobilisation may be more cost effective and achieve a higher impact on reducing child mortality through early identification and treatment.
I hope this helps,
Paul