Darth, the cigars I am looking at making my regulars are $2. Like I said, good cigars don't have to be expensive and expensive cigars aren't always good :)
LWT, basically, I went to a cigar shop and bought a nice tall deep cigar box (a Romeo y Julieta box) for $3. The challenges with using a box like that are keeping the cigars moist because those boxes are mostly going to be IN a humidor, not turned into one.
The box needs to be deep, wide and tall and have clasps. A lot of boxes are deep and wide, but not tall or don't have clasps. You will want all of these feaures to put plenty of smokes of various sizes in
I got one with a cedar block to reatain moisture and to add to flavor. Before I put the first cigar in, I moistened the entire inside of the box with distilled water (you can buy it for a dollar gallon or just boil tap water). I did that several times a day until the box stayed moist on it's own and then I left if open for about a day to equalize out and prevent over moisturizing.
Then, because the boxes don't have perfect seals, I took some felt and superglued it around the inside of the box where the top and bottom halves meet. I stretched it thin to avoid issues with the box closing. The felt costs me about $2, the glue about $3. I got a double osmosis humidifier from my local cigar shop for about $2. They will keep the box at the correct humidity for 30 - 45 days.
That was it. Just like with any humidor, I keep an eye out for mold, too much and too little humidity.