You can definitly do it yourself, but for the OE front springs, you'll need to rent/borrow a spring compressor. The rest is just nuts and bolts. It will take you about 1/2 day to do it the first time. A reasonable install cost I would say is about $300 (4 hours), so if your time is more valuable that that, got is done at a shop.
2007 BMW 328Xi Touring, 6 speed