Upgrading RAM/HDD in latest MBP I planning to buy a 13 inch MBP this month. Is it a good idea to stick to the standard 4GB of ram and 500GB harddrive, and upgrade it myself to 8GB/1TB? This would save me about $350. I have experience opening/repairing laptops, but I never had a MBP.. would this void my warranty?
that's an excellent idea. Apple clearly overprices hardware upgrades. 
And don't worry, it's super-easy to do (be sure to buy a Philips #00 and a T6 torx screwdriver) and it doesn't void your warranty! 
for detailed step-by-step guides you can go to ifixit.com .