What’s the best way to create a low cost garden path on uneven groun

Have you considered pavers? See if anything here excites you.

http://www.diynetwork.com/how-to/outdoors/structures/how-to-build-a-paver-stone-walkway

http://www.diynetwork.com/how-to/outdoors/landscaping/how-to-lay-stepping-stones

https://www.pinterest.com/explore/stepping-stone-paths/

Level the ground as much as possible by removing the grass and large rocks. Old tree roots? Are they part of an old tree thats still alive, or are they left over from a stump removal? If they are left overs I'd chain saw them out. If they're viable then they will determine the height of the path when finished. Next determine your width and cut continuous lines with a SHARP digging spade along both sides. I like 24 inches for width, but thats up to you. Now that you've done all the prep, go to a landscape outlet and buy the necessary length of black polyethylene edging, and a bag of small gravel. Install the edging, and pour out the gravel, starting next to the highest point where the roots are. From that you can determine how many bags of gravel you'll need to finish the job. If the path is long, you may want to enquire about buying bulk gravel by the cubic yard and have it delivered. But if you go that route, you'll need a shovel,(not a garden spade)and your trusty wheelbarrow. I'd also invest in a tamper, not expensive.

Remember to maintain level as you go. Placing a 2x4 across the poly edging will give you a visual reference as you go. Good luck.

I created a pathway from nothing following these steps: 1. spray the grass to kill it. 2. Dig a path the width you want, and dig several inches deep ( I don't remember the exact number) to allow for sand base, rock/gravel and/or stones. This is also when you'll work to level the ground. Once that is done, you'll fill in with base sand and tamp it down, making sure to keep your path level. You can also lay down a weed barrier before filling in with gravel and/or pavers.

Gravel.....

I would dig out all the rocks and save them. I've used every rock I ever dug out of my gardens. Prep the ground as mentioned above. You will use the saved rocks to edge the walkway and to keep the level of sand higher in the low spots. The sand needs to be deep enough so that what ever you use for the walkway completely floats in the sand. If any part of the stones rest upon hard unyielding soil it will make them unstable.

The section of walkway in the picture is made of free bricks from Craigslist. At first my quest was for whole bricks but once I put this piece together I knew I would never walk away from broken bricks again. It took extra sand to raise the brick walkway to the level of the pallets but it was worth it. The edging rocks and pallets in this photo were also free from CL.

The pallet spaces were filled with reclaimed fence boards which is why they are so dark. (they're also wet) I sat the pallets on soil that I had loosened and leveled; I laid solid bricks along-side the pallets to keep the sand in the walkway instead eroding under the pallets.

You can buy sand that has cement already mixed in for filling in the top inch between the bricks. Spray gently to water it in so it forms concrete. This would be best if you want to drive wheel barrows over it. I didn't because I used sand that we had hauled in years ago where our daughter's swing set used to be. I do plan to add the cement mix eventually because I have pine trees and every time I sweep needles I loose sand.

The third photo with the rock walkway is also compliments of CL free ads. I already had the patio pavers, and table and chairs. There are almost always free rocks, pallets and broken bricks for the taking.

https://www.hometalk.com/categories/gardening-landscaping/landscaping/paths