Hi Chris,
The factory ECU with factory 2wd loom is probably the easiest and cheapest option but is only good for a stock engine or the chip upgrades that are available...non of which are prefect for any one car/setup.
Autronic hardware starts at about $1600, add ignition system and components, injectors, installation and tuning and you will be at 3k for a basic set up...add 500R Cdi and 4 cdi coils,$1600, run SM4 instead of SMC, add $600...thats a rough idea. There are alot of other ecus on the market...my best advice is to go with what you can get support for, not what is the best price.
Cheers,
Phil.