All good advice
One of the weak points on all trials bikes that have a link/rocker in the rear suspension is the bearings/bushes in the links.
They are made without a grease nipple to save weight but are often overlooked by owners, if there is a lot of free play, or if they are seized it can be a very expensive job to sort out. Look out for this and price the parts before you make an offer, as a full kit they can be very expensive.
Running a trials bike is cheap, especially compared to road racing, you can send less in a whole year on trials than you would spend in just one race meeting!
Pete