It might just be that it's out of season now (assuming you are in the northern hemisphere).
I'm sure your grocer can get it (probably from Mexico or Guatemala?), so it can't hurt to ask, but it's grown in summer and into fall in the more northern latitudes so that's when it's everywhere. I think they keep stocking butternuts and other "popular" squashes year-round, but spaghetti just isn't as popular (another great reason to ask them to get some!!!) The more popular it gets, the more likely the southern hemi is likely to grow it for export :)
Maybe try another publix?
We got it at our grocery down here in NC.
That's weird that yall don't have it. I love it!
I just saw it in my Publix yesterday!
Try another store or ask them
Maybe you can try Melissa's? They're a reputable online grocer.
...you might even be able to grow them, for next year, if it sucks to find them where you are.
While they may be out of season, you can still get them! I shop around... I even call grocery stores before going to make sure they have it just so I don't go out of my way! I live on spaghetti squash so if I were unable to get it, I probably would have a conniption fit! LOL!