Shopify store for services, not products

It would be a good idea? How should I list the prices for the services? The website will sell digital marketing services like advertising campaigns on social media etc. I think that it's tricky to set fixed prices for our services, because they can be different, depending on the client's needs...then how shoud I set the prices? Any suggestions?

Anyone can help me with an answer?

Does it have to be Shopify only? I know that you can build such a site in wordpress in let's say, 2 days ( excluding the design ofcourse).