I think it will be pretty easy to find a spring pretty close to that. I have a giant coffee can with every size and type of spring you can imagine.
Just start searching the internet for assorted springs, return springs, etc. You'll find millions.
I just did a search and found one nearly identical to that one. Same length with a slightly longer coil stack. It was $19 at Loading Dock Pro. P
What you really need to know is the spring rate and their initial tension.
Dorman Help sells various multi packs of assorted springs , many of which look like yours. You can find them at O Reilly, Advance, Auto Zone, etc. Look at Dorman's site or the part store sites.