Setting a Base Price for a Service with a Variable Selection for Hours Needed

I'm attempting something that seems to be a little difficult. Here is some context. 

I own a video production company. I am often hired directly as a videographer or photographer where I step in, produce the imagery, and hand off the assets thus ending the contract. 

I have a minimum rate that is charged for the Kit/equipment. I then assess an hourly labor rate.

I want site visitors to be able to select the number of hours of coverage they need and the kit/equipment price will already be reflected in the total price. 

Any way to do this in a fairly seamless fashion or would a third party service be better for this?

You can normally achieve this by creating a service product with a variant option for the hours, with selections to suit your needs, for example 1 hour, 2 hours, and so on. Have you tried this?