Dear Josuna,
Can you specified what type of program do you need? If it is for Windows Desktop can be WPF or Windows 8 Store ( metro style, but will run for win8.1 only desktop and tablets ). The program need to synchronize with a database if many users will use it so you will need and server that will do this.
Will have any administration, to manage users and inventory? I suppose yes.
As you understand this is a big project and all parts cannot be written from the beginning to determinate a estimate end time. I can only give you a estimate start time based on my other projects now. I will be available around 30th Jan. Then can start on your project and we will work on agile system. Part by part i will make and we show to you, will discuss if it is right and if you need to change something. This is a better than just to make you a some program on a fixed rate and you cannot change anything there. Now you can put your vision what functionality you want.
And little for me:
I am a individual senior developer with 6 years in .net, certified by Telerik as a C# developer. Online verification certificates from Telerik and past work you can see in my resume. Last 3 years I worked for US based IT company.
If you have any questions feel free to ping me.
Best regards,
Saykor