which will be the best low fees college for btech in cse on the basis of my jee main 85 percentile

Hello aspirant,with this percentile you cannot get into NIT's,IIIT's and GFTI's.You can consider the IIIT's and GFTI's of your own state,you may get some lower branches there.But if you want to pursue CSE in a low fees college then seat for the counselling of your state government colleges.Generally,the government colleges are not very expensive.
To see which colleges you can get ,use college predictor tool
https://engineering.careers360.com/jee-main-college-predictor?icn=QnA&ici=qna_answer