It is quite collectible. As with any currency, condition and rarity add value. A pristine, unfolded, non-wrinkled bill has a higher value.
Google it, there is plenty of info available.
1928-G $2
Quantity printed: 52,208,000
My guess of value in that condition ('about fair') is $6-$8.
The 'variety' would be if this were a 'star' bill. Then my est. of value would be ~$40.
Don in SoCal