How to start with technic?
Here are the two things that I would recommend:


Get yourself a big set if you have the budget for it. These will have a large variety of pieces and once you've built the models from the instructions you'll have a good understanding of a lot of different building techniques.
Watch eBay or similar sites for large lots of Technic parts by the pound. These can be a little hit or miss, but the price per piece is far lower than most other ways of buying parts. Keep in mind that prices tend to be higher around the holidays.


There used to parts packs for Technic like what you are describing, but I believe they were removed now that pretty much everything is available from Pick-A-Brick. You can also get any parts that you want from bricklink.com, and if you don't mind used parts, this can be a pretty affordable option.