Well there are many factors that impact custom app development price, it depends on your budget and needs. I can suggest you to read about custom application development at
https://clockwise.software/blog/app-development-cost/ . You can hire pro devs from Clockwise Software to save both your time and money, they provide software dev services at high level and at competitive price. What could be better. They have large portfolio of their projects so you can check the reviews.