A friend asked me what was the best way to attract pollinators to her garden. She was thinking about getting a honey bee hive or maybe just attracting native bees.
1) find a beekeeper who needs somewhere to put hives, honestly you should not have to pay for this, someone will appreciate having somewhere to put them (we are always looking for good places to put our bees, particularly if you have lots of trees or other sources of nectar nearby), but you will need to be ok with them visiting every few weeks in spring/summer to check the hive. And they might give you some honey.
2) native bee/wasp hotel - this is for solitary bees and wasps (they just lay a few eggs in holes in wood and the new insects hatch and forage near the hotel, providing both pollination and pest control as some of them eat caterpillars too) and it does help to attract pollinators if you give them somewhere to live.
3) native stingless bee hive - there are three species of Australian native bees that build colonies like honeybees. They prefer warmer temperatures, so you'll only find them in Queensland and northern NSW as far as I know. They have a queen (or several) and live in hollow logs etc. They don't fly very far, so if you've seen these in your garden then you already have a wild hive nearby. You can buy hives at around $200-300 for a tiny box of bees.
If you don't want your own honey beehive, then I think the cheapest and most effective option is to make habitat for wild pollinators that you don't have to look after or pay for. As long as you provide lots of flowers all year for them to feed on, shallow water sources, habitat (bee hotel, hollow logs, trees etc), no spraying of chemicals, they should come into your garden naturally. The options above will boost numbers if you feel that you still don't have enough pollinators.
What do you think? How do you attract pollinators to your garden?