It looks very similar to the spring used in my Echo weed eater, the spindle at the end that holds the cutting twine. You tap the end on the ground while it's spinning and it lets a new length of line out. The spring inside looks almost identical to the spring you're looking for. If you have a lawn mower repair shop, better yet, an Echo dealer anywhere near you, check with them.
However, by the time you get done running around, going from store to store, you may just end up spending more in fuel than if you just purchase it on line and the right one shipped to you. It's possible, even if you find something on line, it may look right, but it could be the complete wrong size.
Another thought, go to your local RV dealer, to their parts store and see if they have one.
There again, I hope it doesn't cost you a dollar to save a dime.
Good luck.