I would start by checking several libraries near you, a lot of libraries nowadays are putting in things such as sewing machines, 3D printers and I think sometimes even laser cutters, you can get 3D models to print at websites such as
Shapeways and
Thingiverse or even make your own with 3D modeling software or a 3D scanner.
If you would rather make something entirely by scratch with your own hands you could do what I did for my first few props, make them using hand tools out of a 4x4 of pine lumber that you can buy for about $8 (at least in the Midwest US area) and could make about 3-4 lightsabers if you find one without too many knots.
I got 2 beautiful, high quality wood planes for about $25 each at a flea market, now I know that isn't super cheap, but I wanted a high quality tool. You could probably make a wooden lightsaber with nothing more than a drill, saw (I like a coping saw because it can cut curves), an Exacto handle and several blades, some files/wood rasps, needle files, a drawknife and a vise bolted to a sturdy table. All in all I'm guessing you could probably get what you need for about $70 and you can make almost anything with that. I should add that this isn't the absolute easiest or cheapest way, but in the end you get a solid feeling and good looking prop.
Check out youtube channels like Tested, Andrew DFT, Volpin Props and AWE me for a bunch of prop making advice, tutorials and full builds. Also feel free to ask the people here on the RPF for any advice you might need, I've found that people here are
very helpful when you need advice.
The biggest piece of advice I can give is to just have fun with it, don't take it too seriously or your hobby just becomes a job. Something to be aware of is called the good, cheap, fast triangle, pick 2, you can have your prop good and cheap but it won't be fast, you can have it fast and good but it won't be cheap, this basically just means that it depends on what you want out of the prop, if you want it to be really good, then you need to sacrifice either the cost or the time. I generally lean towards good and cheap, thus it takes me a lot of time.
Here is what I made with about $20 in material costs (lumber and paint). This is technically my third prop project, but it's still one of the first.
View attachment DSC_4655.JPGView attachment DSC_1205.JPG
Here's the link to my build thread:
http://www.therpf.com/showthread.php?t=271691
Also a Video of how I made it:
https://www.youtube.com/watch?v=U5U8vobK0c8
Again I know this isn't extremely cheap and it's not extremely easy, but it is technically a beginner project as it is one of the first things I've ever made. If you're looking for something even cheaper and even easier, I'm afraid I can't help there as this is basically all I've ever done.
Best of luck to you, this is a wonderful hobby to be a part of!