How many miles were on it when you got it? Is it safe to assume you've changed the timing belt already? That's a critical maintenance item with these engines (major engine damage if the belt breaks).

Do you do any repairs yourself? (Valve cover gasket replacement is pretty easy & cheap.)

I always told my friends (who don't do any of their own repairs) that they should budget around $750 a year for repairs/maintenance on a used car about this age.