if you're talking about buying a block of say 100 hrs to boost your total time then I reckon it will improve your chances of getting a job, the more hours the better in this game.
But why buy hours when you have already got a CPL you spineless muppet. Spend the money of getting an FI rating, or get hours by........ working! Banner towing, parachute dropping, aerial photography etc. All good sources of hours and a lot easier to find than an airline job if youve got anything about you.