I'm not super suave on the g3's and pricing, but I can't imagine they are too sought after or HTF as I always seem to have a surplus of them on hand, but I'm not 100% sure. If she is though, I'm rich! 'cause they always seem to make their way to me.
I don't know about the tiny tin, but from my experience, neither Sparkleworks I or Sparkleworks III are rare... sorry. :| Most common G3s are selling for around $3 these days... some up to $5...
The only Sparkleworks that are somewhat harder to find are variants of Sparkleworks II that have the reversed symbol. One came as bonus pony to Loop-de-la and the other is the matte one that came with the Ballet Fun dress up pack.
well as sad as it is to say... a lot of people aren't even paying $3 for common g3's....I've found a number of mint ones for $1 because the people have to many of them and just want them gone...