Conditional price in readonly text field I have a content type to create membership for a plan, There are around 900 kind of price based on condition. I know conditional field only make visible the text-field when criteria match but if I create text field for each price then my content type will have more than 1000 fields and that is some kind of fussy isn't it ?

So can anybody suggest me any other option to do it, like I know first 4 condition, based on which the value has to come, I can make table for it...but how to go forward to make it appear in content creation page ?
Looking at your requirements I would suggest going with the data module

You could create a table with all the possible combinations. Once that is done in your content type you would be displaying the required fields such as Apartment Type, Plan Type etc. When the content is chosen you can look up in the table and get the correct pricing. 

There are some assumptions made here. The prices are fixed and known in advance and changes in price would be minimal. We only need to get the correct price defined byt the table. 

As for the down payment and EMI I presume you would have a set rules for the same which can be calculated on the go.