I do and/or have done a bit of graphics and video editing over the years.
What's worked for me in the past:
OpenShot
GIMP
There are some decent tutorials on GIMP so you can apply some of the same
techniques to make your images look near-perfect. They may not come out quite
as professional-looking due to time spent and/or skill, but in my experience
the average person won't notice anyway. Most people will be like "You did
that yourself? How'd you do that?"
Here is an example on how to take a product and make it reflective similar to
what professional graphics designers do for large companies (ie Apple, Sony,
Microsoft, etc):
http://zoffix.com/other/Gimp-Tutorial-Reflections-of-Non-Flat-Objects
Basically if you can follow the directions you can create some pretty
impressive looking material.
Here is a brochure that I made (older version which is out of date, but
none-the-less) using all free software:
https://www.thinkpenguin.com/files/brochure-5-25-13.pdf
Or an example of the reflection effect in action:
https://www.thinkpenguin.com/sites/all/themes/B7/images/front_page1024x768.jpg
The brochure took the most time. The reflection takes a mere 10-20 minutes
maybe at the most. The more time you put into it the better you can get it
too. A lot of the stuff I've done was more quick and dirty to get the job
done, as I just don't have that much time and I have more important projects
to work on/coordinate/figure out how to finance/etc.