Cheap Bluetooth headsets do exist, but bear in mind that you're not going to get a top-of-the-line product for the price. For example, the LG HBM-235 is as basic as Bluetooth headsets come these days, with no A2DP streaming, and without a fancy design. But it is very affordable at only $39.99 retail, plus you can get it for as low as $19 if you shop around online.
The LG HBM-235 headset has a simple look. Measuring around 1.8 inches long by 0.7 inch wide by 0.2 inch deep, the HBM-235 has straight sides all around and a very minimalist design overall. A skinny volume rocker sits on its right spine, while its Micro-USB charging jack is on the left, covered with a simple plastic flap. There's nothing on the front surface save for the LG branding when on standby mode. When the headset is activated, though, you'll see a tiny LED indicator glowing beneath the surface.