That's one of those "it depends" questions. Places like Pediwear or Shoe Healer take off VAT and offer free shipping and maybe free trees depending on what you buy. If you can avoid customs/duty (try and get them to ship royal mail/parcelforce) it's easy math as to what you're saving plus you don't have to lug home some heavy ass boots in your luggage. If they ship UPS/Fedex you're looking at a likely charge of $25-30 in brokerage fees plus around 9% duty. DHL fees are around $12. If you buy in person as a tourist you should still be able to get the VAT refunded provided you jump through the appropriate hoops when leaving. Try to avoid those companies which offer to process it for you as they charge a percentage of your refund. As CTBrummie says, you also get the big advantage of being able to try them on which is a big deal if you've never tried them on before. You may or may not get hit with customs/duty when returning. But I've never been charged with any while returning to the US even when I've gone well over the duty free allowance. Just be sure to declare everything. Another thing to consider is that the Jermyn Street shop is likely to have some interesting make up not available anywhere else.