Hi candidate! The fees for droppers is around 1 lakh. The fees also depends upon various factors like how much you will get scholarship for the institute and it depends upon the number you get in your NEET examination or the number you achieve in their admission scholarship test. The fees also depends on which Allen institute you want to take admission.

You should have to make contact with the institute in which you want admission so they can provide you enough information.

For further information you can go through this links-
For Neet-
http://www.allen.ac.in/neet_ug_aipmt_premedical_aiims/neet_ug_aipmt_premedical_aiims_fees/neet_ug_aipmt_premedical_aiims_fees.asp#leader
For jee mains and advance -
http://www.allen.ac.in/jee_main_advanced_IIT/jee_main_advanced_IIT_fees/jee_main_advanced_fees.asp
Hope it helps.

Thanks.