The rules on Trapmaking are for dungeon use. DO NOT use them for snares, pits, deadfalls, and nets. Only use them if a trap must actually be MADE (such as if your Rogue wants to hammer out a beartrap in the forge).
To find food in the wild is a DC:10 Survival check. Survival manuals are full of snares, pits, deadfalls, and other such mechanically-simple traps which can be easily set. Thus, I use a DC:10 Survival/Craft (Trapmaking), and no penalty for lack of crafting tools, so long as the PC has a knife (and handaxe, for some traps).
The prices for traps in the DMG are ridiculous. Remember: Time = Price = Quality. It takes very little time to make a crude trap, and it isn't worth much of anything, just like it is ridiculous to charge the same amount and length of time for a stone axe as for a metal one (no one would buy a stone axe at the same price, if the metal ones were available)!
I remember when I set my very first tree-branch snare... It didn't take anywhere near a half hour, and I wasn't even sure what I was doing! All I took with me was a piece of string, and a pocket knife. The rest of the things I needed I gathered from the tree that I used to set the snare! A few minutes later, I had a simple snare that, when some critter came and took the bait, would wrap around it and lift it off the ground, dangling from the end of a tree branch!
Cost? Maybe 1 CP for the string! Time? Maybe 10 minutes (much, much less, now). If realism interests you, a roll of snare wire, in real life, cost me 50 cents (under 3 CP), and had four colors of wire (Dark Grey/Black, Olive Drab Green, Sand, and Yellow), 40 feet of each color, for a total of 160' on the roll.
As for concealment, I make the PC
Hide the snare, and then use their roll as the Spot DC. Disarming a snare (which can only be done once you've found it) is about DC:2. It's very difficult to fail!
Now all of this is based on REAL LIFE, not 3e...
As for your bell trap, as originally listed, boy would you be in for a surprise, first time you ever tried to use it! I'd check my Weather Table for the day, and on anything but a "Dead Calm" result, you'd find out - real quick! - that any little breeze would set a bell on a piece of wire rattling! If you have a bell handy, take it outside and hang it up. The bigger it is, the less you'll hear it, but small alarm bells are going to go off with ever little breeze!
What I used, once upon a time, was a series of small, clapperless bells, tied to the wire. They were far enough apart not to clang into each other when blowing about in the breeze, but were also close enough together to jangle loudly when the wire was run into. This worked well enough when one of my buddies ran into it.
Also, if you're going to go to this much trouble, you might as well make three or four traps, with different bells (one of steel, one of silver, one of brass, etc). Then, you can set one up on three or four sides, and the difference in sound will tell you which wire got hit (and thus which direction to look towards).
|-------l
| Camp l
|______l
Something like that...
Another good trick is to use some simple snare wire and a couple of screw eyes, loop them around some trees surrounding camp, and then attach them to your rings, at night. When something hits the wire, you'll feel a tug on the hand on that side, giving you a SILENT warning, and at least the hemisphere from which the intruder is entering...
Of course, in D&D terms, Beholders, ghosts, most serpents, flying/levitating critters, etc., are just plain not going to trip a tripwire (or a snare, or most other traps)! So...
![:]](http://www.enworld.org/forum/images/smilies/devious.png "Devious :]")
