Assuming the updates are coming soon, if I bought a MBP this week, should I buy a really low end model or high end model? In terms of value depreciation, which makes most sense to get?
Because all MBPs use tue same GPUs I would get the low-end model but in the end it comes to your usage. Buy the model that suitsia best for your needs as they all will lose value by about the same percentage
Before they made Macbook "Pro's" in 13" and without good GPU's, the cheapest Macbook Pro was $1800 on student discount, $2000 without. I'd buy mine for $1800 ($1916 after tax), and JUST before or JUST after the new one came out, i'd set it all up with the best free software, and include the InCase sleeve I bought for it, and get all of my money back.
I still do that to this day with the iMacs, and it seems to work well. Free upgrades for a little bit of work (wipe/reinstall, configure, etc) are always welcome.