Bobber-style indicators, such as the Thingamabobber, are nice but can be expensive. Yarn indicators are quick and easy to make durable, land softer and can be almost as buoyant.
Simply wrapping poly yarn with thread can be done in under a minute to yield a simple, and effective, indicator. Best off, they're free and can be customized in any colour you want.
Instructions after the jump...
The simplistic version can be tied in only a few minutes, with any form of yarn and thread.
If you're really on a budget, any ordinary knitting yarn and sewing thread would work here, but chances are you already have poly yarn, thread, and a bobbin on your desk ready to go.
Additionally, an optional final step is using glue to secure the wraps. Superglue is cheap and easy to work with, and should already be a part of your tying kit. If its not, make sure you buy the bottle with the brush on applicator, its far easier to use and will have a far longer usable lifespan than the applicator tip.
You can use any yarn you want, but be warned that many yarns (such as wool, cotton, and acrylic) will wick up water and become a sinking mess. Poly yarn is water resistant, and will accept paste floatant happily and hold onto it. The colour choice is entirely subjective, but I find myself preferring orange yarn as its much easier to pick out. Yellow, white, or red, whatever colour or even blend you find easiest to pick out is just as possible here. Additionally, a few strands of Krystal Flash can be worked into the indicator to provide a little extra sighting cue.
These indicators will require the occasional use of a bit of paste floatant (ie, Gink) int hem from time to time. You'll find that if they start to sink, just wringing the water out should give them a bit of life, and really grinding the Gink into the yarn will help it even more so.
Unfortuantly, the biggest downside is that if ice is forming on your guides, a yarn indicator is doomed to fail. You're going to need to purchase or come up with a different solution, but if you're looking for a quick and easy indicator that costs next to nothing, try out a yarn indicator.