reusable cell culture flasks, pipettes etc. - (Sep/12/2007 )

It also depends on what you wash your glass with.
Detergents can be nasty on cells.
Sulfo-chromic mix is an environmental nuisance due to heavy metals.
Piranha solution (H2SO4+H2O2) can be dangerous but can be diluted, neutralized and disposed off.
15 pipettes and 4 flasks are probably friendlier.