Questions regarding PostgreSQL

To Whom It May Concern:

Thank you for your attention on this email. I want to know if PostgreSQL is the right program for me to buy or not. I am now starting to do a project on designing a database. The simple picture of the project is as follow:

Project (ID) ----Staff (ID)
| |
Reporting Working Hours
(Billing)

This is quite a simple database design, for which each project has its permanent ID. Each Staff has his own permanent Staff ID as well. Their working hours have to be recorded. And the fee of each project has to be recorded as well.

I am going to buy a software to design this database on LINUX. I am wondering if PostgreSQL is suitable for me or not.

Thanks for your attention. Please get back to me as soon as possible.

John