There isn't much about their potential value, as the
beauty & desirability is in the mind of the beholder...
If the unit is accurately described as FlowerPower:
• iMac G3/500 (Early 2001 - Flower/Blue)
Other specification models seen from this index:
http://www.everymac.com/systems/apple/imac/index-imac.html
For much newer models of Apple product, this site will show
current (twice yearly?) price estimate. This is too old for that.
Fewer vintage and obsolete reseller pages appear online
however I've seen some of these that look sharp and run
in a complete kit in local ads. You may get more than $20.
Especially if it has an original box in fair condition.
To realize an asking price, depends on who happens to be looking at the time. 😎