You can't tighten them, buy another one, but it may not be the handle that's loose, it could be the winding mechanism itself is worn. Or as you say, instal power windows, I did about a month ago, not as hard as it seemed.
I bought the regulators, door looms and switch from ebay for about $220 second hand. They are available on ebay regularly as a complete set. Since you have an Acclaim you should aready have the connector for the main switch, the connectors for the relays and fuse already wired up to your BCM. I have an Acclaim and all those things were there ready to go. You just need to replace the door looms and instal the regulators, buy 2 relays and a fuse, plug in the switches and that's it. You also need to buy new rivets for the regulators from holden, $40 for 20 rivets (rip off)