Yes, some science experiments are expensive. The question is ‘what do they contribute and are they worth it?
Here are some that have cost HUGE amounts of money
1.the moon landing
2. the Manhattan project (designing and building the first atomic bomb)
3. the particle accelerator at CERN (You will have heard about the Higgs boson – this experiment aims to understand sub-atomic physics answering fundamental questions like where mass comes from)
4. the human genome project (understanding the code that DNA is built from)
5. international nuclear fusion reactor (adding small elements together to form larger ones and release energy in a controlled way – this would solve the world’s energy problems)
6. Various telescopes and arrays to study the cosmos and our place in it
All of these involve hundreds if not thousands of scientists working together to solve problems – with varying degrees of impact for good or bad
Shane’s answer is awesome – he covers most of the really expensive experiments. But like he says, just because its expensive doesn’t mean its the best. There are plenty of very inexpensive experiments that have been done that are really important as well!