There are a lot of free Joomla templates available on the internet. to use on your Joomla website. many of them are quite good. There are a number of template library websites where you can browse the templates, often view demos of them, and download them if you wish. All for free. Then, you can customize them with your own graphics, logos, etc. as you see best.
In addition to these libraries of free templates, many of the commercial template providers have a few professional quality templates that they give away for free. They want you to sample the quality of their templates as well as making a contribution to the open source community.
In addition, some template providers will give a template away to non-profit organizations for free if a link back to them is put on the website. They don’t generally advertise this, but send them an email and ask if they have a program like that.