The VAG 401 is expensive??? Call that a matter of opinion I guess. It's $58 CDN on Amazon, paid around $300 for my other OBD2 so I thought it was fairly cheap.
Thus far, I've used the 401 to read and clear DTC's, and pull the code to program new keys. It WILL do adaptations on the car as well...check out the videos on youtube.
The 401 will NOT give you a graph to assist in setting your pump timing/start of injection. Have not dug into it enough yet to say for sure whether it will give you fuel temp and timing numbers (I think it likely will)...which would allow you to use that thing between your ears and do the job sans active graphing.
Important to note, that manuals and support are SEVERELY lacking for the 401. ie...virtually non existent, which means you're largely on your own with it.
VCDS or VAG-Com ARE well supported, and there seems to be a large number of folks who have it and use it...so getting help should be far easier.
Depending upon your intended level of "involvement" with your car, choose accordingly. I got the 401 AND Vag-com. I find the 401 to be handier than a laptop for minor stuff.
Regards,
Al