What is estimated budget for apps like Follower Plus or InsTrack?

I would like to make an app like Follower Plus or InsTrack

I want to offer this app to my clients for FREE.

so My budget was around $5000....

But the developer said $40000 for this kind of application,

and I am not sure if this is a resonable price.

I don't want to make money, I just want to supply a great extra service to my clients with no charge.

40000usd is reasonable price for an app like Follower Plus?


If so, I need to find a way to pay. ;(