I want to get all my old VHS, 8mm video&film and laser
all into my computer in a fast inexpensive way.
After all this transferring I'm sure I won't need the equipment much.

I don't want to get into the habit of being the family transferer guy.

So should I buy a used Sony digital8 with firewire & AV input?

Or should I just do it real with a used Canopus ADVC110?

I say get the ADVC converter. You can use it to transfer all your tapes (8mm and VHS, as opposed to D8 which can only transfer 8mm - and not all models!) and when you're done you can sell it.