Welcome to the Do-It forums Spoonie!
Personally, I use the CS Coatings Seal Coat on anything on a jig that needs sealing. Powder paint requires no sealer, unless eyes have been added after the paint has cooled. Diamond Coat (sp) is a popular top coat but it too has an odor. As you've alluded to the nail polish thing will work in a pinch. Lure Works makes a number of solvent based sealers but one has to take care with anything solvent based as the sealer may attack the eyes themselves if that is what you are sealing. CS Seal Coat has no solvents or odor and does an amazing job.
I air brush several of the more detailed jigs and use the CS product after the paint has been heat set and have zero issues with it.