That does seem extremely expensive compared to similar group tuition events. £250 for two days of tuition (Sat 10am-6pm and Sun 10am-5pm according to the site). It's also not clear exactly how much time within that is allocated to classes - I can't imagine it's going to be 7 or 8 hours solid teaching time.

By comparison the tuition element of the Sore Fingers Bluegrass Week is £240 - for FIVE days of group classes, around 4.5 hours per day. Top bluegrass and old time musicians come over from the US to teach each year. This year's tutors include Jim Hurst teaching guitar, Tony Trischka teaching bluegrass banjo, Matt Flinner teaching mandolin, Bob Carlin teaching old time banjo just to mention a few. That sort of level of cost seems reasonable to me for what you are getting - just under £50 a day for group tuition.