yeah the xbox was fine.. only the psu got burnt.. im sure if thats what happened with you then ur PSU will be burnt only too.. so either get a new PSU or get it repaired.. i dont remember exactly how much it cost me..
Btw i suggest that you buy a new PSU instead of getting it repaired.. my xbox's graphic chip got burnt 2-3 months later now im not sure if that was because my PSU was repaired or not.. Might have been cause of that