Most definantly, i had no idea when i bought mine, but i learnt very quickly. all worth it though
you have the standard costs, i.e. insurance, rego
then the extra fuel a turbo uses.
once you start the mods, there is the initial cost of that mod, then you will need 2 more mods to support/compliment it.
In most cases it will induce some underlying problem to show up, so that will have to be fixed. and thats just one basic mod.
do that a few times and you very quickly pass the $10k mark