Hello,
I'm fairly new with ubercart and drupal so forgive me if this suggestion has already been implemented. My suggestion is to add a shopping cart specifically for work done by a contractor. For example, adding the number of hours worked, type of work or description of work and hourly/salary rate done by a contractor such as a software developer, construction worker, accountant, barber etc...
So, there would be line in the cart such as the following :
hours worked | rate | description | total
10 hrs | 30/hr| developed web site | 300.00
5 hrs | 30/hr| update software module | 150.00
-----------------------------------------------------------
15 hrs | 30/hr| * | $450.00
- Alan