Without knowing the type of bike you will be performing the work on, it would be hard to say. The parts you mentioned like the chain can be bought for as little as $14.99 or as much as $100 and the cables for as little as $5.99 to $70. I think you probably need to get an estimate form the bike shop on your parts you want to replace with labor and then figure out how much you're willing to spend on the bike, depending on the condition of the bike you may want to re-think your options.