Well, you also say the cheapest. I haven't done any sort of 'sampling' based on least expensive. With this sort of thing, you either like it and use it or don't like it and lament the purchase. If you're knowingly limiting your purchase by the criteria of "cheapest", it's likely that you're also limiting the likelihood that you'll be pleased with your purchase long term. But, that's just my opinion; and buying the more expensive doesn't by default equate to buying the best. We're only talking about a $10-$20 difference in price on most of these things though. I'd recommend reading reviews and then buying based on what looks compelling.
Here's a link to my latest Bluetooth headset. My comments are based on initial experience; no long term use. Check Rossman's posts for good pricing. There are also comments about the Motorola HS Series BT Headsets. The 810,820 & 850's have received some play here in ATOT. Note that in my comments I rave the Plantronics compared to the Motorola's but that doesn't mean the Motorola's are bad, especially comparing price.
*Linkage: Bump back up to Rossman's post. He's already linked the thread I mentioned.
RossMAN, thanks for that V510 review you linked. I wish all gadget review sites were as thorough. Good reading.