SOME money, assuming you can find buyers prior to buying in parts, buy parts then add margin and sell.
How much money is anyone's guess but my guess is "Little to none". It depends whether people see the margin you add for the service you offer as value. You will find those who appreciate the difference between a good custom build and a pre-built off the shelf will have the know how or inclination to do it themselves without the margin.
Anyone who does not know how to do it themselves will not care for the benefits a custom build brings so will unlikely buy into your product/service.
Selling hardware does not make the money, the after-sales service, warranties and all that pap is what generates income.