I placed a small order with SJS Cycles today, as the rate at the time was about USD $1.35 compared to USD $1.65 a short while ago.
I use XE Currency Converter both as a Web app and Android app. It kept crashing last night, trying to keep up with the rapidly changing exchange rate and the massive increase in server traffic as everyone checked rates.
The GBP rose about 2 US cents against the dollar as the day wore on, one penny just this evening, so there is some recovery already.
I paid with PayPal, who nicked me about 3 US cents over the exchange rate, but this was better than my credit cards, some of whom allow they will apply the interest rate most favorable to them within the last 24 hours. That would have been based on yesterday's pre-Brexit rates, eating up any savings for me, so PayPal was better.
I wish I could place an order for a second Thorn, but it just isn't financially possible for me now. For those who can, act fast. This window of opportunity for foreign buyers of UK goods priced in pounds will likely close to some degree very soon.
Best,
Dan.