HI,
Its Simple you got some calls from institutes right so follow below steps.
->Check what are the topic's they will cover.
->Trainer Exp in SAP.
->If possible google it that institute and see the rating and comments.
->Last but not least just compare the cost institute to institute
(as per my idea in Hyderabad :10K - 25K in Bangalore 15K - 50K ).
http://scn.sap.com/thread/871124
If you have any q's let me know and i hope you understand the above process 
.
Regards
Mahesh