There are a lot of seafood lovers out there who will eat lobster all day long and not bat an eye, but as soon as you mention crawfish, they turn up their noses. In fact, the crawfish is basically the freshwater cousin of the lobster, even to the point of tasting pretty similar. Filling a dish with crawfish, or crawdads as they are known to some, and "yabbi's" to our Australian buddies, is a very tasty culinary adventure and can save you a lot of money over the salt water cousin. One problem with crawdad fishin' is that not everyone knows how to catch the critters or what to catch them with. I am gonna give you some advice that will help you put crawfish in the pot, and should save you a lot of money too.
Begin making your traps by finding some old 2-liter bottles. It doesn't matter if they are two or three liter size. You start by cutting the screw top off just a little below where the neck starts to flare out to widen the mouth (opening) just a bit. Next, you want to cut the whole top of the bottle off at about a half inch below where the flared top stops, and the flat sides begin. After that, you take the top portion that you just cut off and turn it over with the mouth facing into the rest of the bottle, and insert it until the two sides meet up and touch each other again. Now with a couple of hole poked through the edges where they meet, and a few tightened twisty ties (same as off your loaf of bread), and you've got a crawfishin' trap ready for the water. It helps if you poke intermittent holes along the length and around the trap. This helps it to sink better and will help with the scent release after you've baited it.
As far as bait is concerned, opinions are as varied as the country you might be fishing in. I have heard a lot of guys swear by bacon, turkey pieces, cat food or tuna cans with holes poked in them and even leftover table scraps. I personally have had the best luck with fish heads and guts. I will always anticipate crawfish trapping while I'm out fishing, and when I get home, I throw all the heads and guts into a milk jug with the top cut off, and put it all in the freezer for crawdad bait.
You can spend a lot of money on supplies for catching crawfish or anything else in the water. As for me, my budget is pretty restricted so anything I can make at home with what I already have is a huge help.