Main pivot frame bearing??

mark62

My son uses a 2005 Trek Liquid 30, the main frame pivot/bearing (think thats what its called) has developed alot of play in it. Is this an expensive repair, or am I better looking out for another 2nd hand frame (seems like a lot going for £200ish). Apart from the play in the pivot, its been a decent ride for him. Also, is it potentialy dangerous to carry on using with this play in it? Any thoughts??

Cheers