I have a sextoys theory: Sextoys(.)co.uk could have purchased Sextoys.us because they deal with the USA under the domain Sextoys-USA.com! Sextoys.com would be a HUGE some of money, so .co.uk & .us just about covers it! Then the .mobi gets a good offer! They would have covered their market, mobile, us & uk. For a domainer the $50k would seem like a lot of money but for this end user, it's a price worth paying because they can make their money back easily by actually selling their products rather than advertisment ect. A good investment for the end-user.
Or a rival sextoys company could have paid the hefty price because they need to start making more sales. At the end of the day, theres no better domain for selling sextoys than sextoys.whatever now is there! These domains are rare for the traders so don't sell cheap imo. I wouldn't anyway!
Sextoys.info $10K+ IMO. GL