You may have hit the nail on the head by thinking popularity has an affect on the price. The retail price is what the market will bare and you have been in two different markets. The only thing to do is find a reputable retailer and research the average price for the market place you are in.
The classifieds here are a good place to find a decent used razor and have used it myself with good results. Keep in mind that when you import things you may be liable to customs duties and or VAT so a little research there might be useful too. I am sure some of our UK members can fill you in on that score.
Bob