Pricing for custom work [closed]

I’m not sure if this is a better exchange for this, but here it goes.

I want to talk to you about pricing for custom work. I can only assume you get just as much (if not more) request for custom services. I land a good amount of the jobs but I loose some too, with clients saying my pricing is ridiculous.

Here is an example:

A client wanted me to update his custom made product that was made for him in 2013 to be compatible with PHP 7. I opened the product and every plugin was base64 encoded and not only that it was jumbled using variables and even false variables.

The first thing I did (without telling the client) was decode the mess (to be sure I could) once I had it decoded I also found out it was in another language. And I left it at that.

I responded to the client and told them I would charge 100 – 150 USD to decode / translate / update his product.

I base this price on my demand, internet research for custom coding, my family of 5 to feed, and the time I have and will invest into the project. With my final price already in my head of 115 USD (so he feels he got the lower end of my estimate) just a business trick.

I know this project wont take me more than 2 hours, but I also have a lot of other projects going on and a family to feed. I feel my estimates are fair based on the supply and demand for them.

so my question to you is how much would you charge for providing such service?