The Sliced Invoices core plugin is FREE and you can download it right here:
Sliced Invoices v3.9.1 for WordPress
The free version of Sliced Invoices has all the features most people need for basic quoting and invoicing.
Need more advanced features? We have many free and paid extensions available.
You also have the option of buying a “bundle” package which gives you many extensions at a great discount.