I sold my (genuine UK origin) Mariah 218Z with new full camping cover and UK legal trailer for 6.5k a year or two ago. I prob let it go a bit cheap, it only had 220 hours on it, but there are bargains out there such as mine.
The pre 2006 Mariahs were very solid boats, they went bankrupt and another company purchased their name and sold cheaper boats based on their previous reputation.
However they were not perfect, the hulls were very solid but they claimed that the fittings were mainly bolted in, we found they were typically screwed into the GRP same as any other. Generally ok but a few pulled out over time, so yes solid boat but look at them like any other for faults.
It also sucked quite a bit of fuel when skiing etc with the 5.7LX. Great cuddy boat but I have since concluded that because of its size it was expensive to run than a typical sports type day boat, but without any proper head facilities it wasnt really an overnighter / weekender either. I wouldn't go for that size again, get one or the other unless the cuddy without a head is something you still want after considering this point.
'There is nothing half so much worth doing as simply messing about in boats'