Well, depends at what engine revs, the belt snapped. Might just need a new head, or the odd valves, replacing. Might as well, take head off for inspection. Then take sump off, check the rods, and bearings.
This could be a cheap rebuild. or an engine swap. What are you looking at price wise, to take swap head, and check bottom end? £500-£600? Swap engine, £1000? Or, are we taling more?
Andy.