Shrink Plastic probably isn't a big search term so there is no reason to have it in your title (at least from an SEO standpoint, double check your stats to make sure a lot of people aren't actually searching for it). I'd use the title to describe the individual items / style using words that you would search to find it. IE:
"Rabbit earring, shrink plastic stud, illustrated rabbit head"
...could be...
"Rabbit earring, hand illustrated rabbit head, stud back"
Or something like that. I don't SEO to jewelry ever, so I don't really know common terms people would use to search ("rabbit earring" actually returns a decent number of results, more than I initially thought).
As for "Shrink Plastic" sounding cheap, nah. Just don't call it "Shrinky Dinks". Like Amanda said, definitely describe the process, I remember from my childhood it is actually pretty awesome (and fun to watch)!