My V3i came with wireless headphones. Simply fantastic to use, for example my first hunt with the detector saw me driving home with them on because I forgot to take them off! Done the same a few times since then as well. It is great to have the freedom of movement by not being attached to the detector all the time.
For retro fitting a detector, I have heard to be careful with bluetooth systems. It is not interference that is the problem but a time lag between the coil registering a target and the headphones sounding the tone. Having the coil a couple of feet past the target when the headphones sound of would make hunting frustrating. The older wireless non-bluetooth types sound like the ones to go for.
Remember though, that with wireless phones you will need to use extra batteries to power them. The V3i's last 20-30 hours on rechargable AA's but after having them run out on me a couple of times I now carry spares just in case.
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