There's an Icebreaker factory outlet near where I buy underwear. It's coming out of winter here, so there might be a lot of stock there at the moment. I'm guessing with the deadline of your boyfriend's birthday, coupled with the weak Pound, it wouldn't make be worth it. Even if it was a deal, I still think it'd cost GBP50 - GBP70 incl postage. But let me know if you think it's worth pursuing while I'm out there, looking for underwear. Which, fyi, New Zealand does excellently as well. If I was sending him an Icebreaker, I'd recommend upsizing to a 'Bendon' underwear combo, they're GBP5 each. If you're interested, let me know his sizes, and maybe any links from the Icebreaker site.
Otherwise, this is one of my winter designs, it's about 6 pounds incl postage.