it's cliched but if you have the time and some tools, i would say you win if you do it yourself.
the main things i found for the sub are:
1) routing the power from battery thro the bulkhead, left hand side of the car
2) routing the audio from behind the radio, finding a path for it just over the pedals and down the right hand side of the car
i had some time free, and i borrowed quite a few tools from work. i also had to be patient as i didn't get sound instantly as it took me a few days to collect the right tools for the job