Headlights for a BMW E39 can be purchased at various website which include but are not limited to Amazon and eBay. Car-Tuning stores also sell headlights for BMW.
The BMW 525 was introduced in 2000. It was made until 2003 and then it was replaced by the BMW 525i E39. It cost around $25,000 new and a used one is $8,000.
One can purchase a used convertible BMW at most online car shops, "truecar" or "gumtree" to mention some. One can purchase or at least order a convertible BMW at any BMW office.
One can purchase a BMW 2006 3 series at your local used dealership or BMW dealership. One can also find them for purchase on sites such as Craigslist.
One can purchase a BMW diagnostic cable from several different places. Some of the places in which one can purchase a BMW diagnostic cable are: Amazon, Target, and Walmart.
You don't state what year, but for the E39 (1997 - 2003 MY) there is one in the trunk on the left side in the battery compartment and another in the glovebox.
One can purchase BMW rims at several retail locations and from a variety of people who own the rims and are willing to part with them for a price. To ensure that the rims are authentic, one should purchase either directly from BMW or from a BMW authorized dealer.
Someone that is looking to purchase a new BMW can do so by visiting the BMW company website and using the link to find a BMW dealership in one's area. Another option is that one can order the BMW at the company website.
I would imagine it depends on your chassis. For the E39 (5-series 1995-2003), there are two different belts for the ac and alternator. One runs the A/C Compressor and the other runs the Alternator, Water Pump and Power Steering. Here's a link with a good belt diagram for the E39: http://bimmerboard.com/members/cn/E39-drivebelt.jpg
The best place to purchase a BMW M8 would be at a local dealer. Also, their website allows for the customization, purchase and delivery of BMW M8 cars.
One can purchase headlights for a Honda Civic, directly from a Honda dealership. They can also be purchased from auto part stores. Many stores like Walmart have an automotive counter where you can get these headlights. One can also purchase them from an auto recycling business. They usually carry both new and used headlights for the Honda Civic.
A used 2002 BMW can be purchased at a BMW dealership. This would depend on the availability of that vehicle though. If none are available on the market, one cannot find one to purchase.
One can purchase allows for a BMW from a number of retailers. They are available to buy from eBay, Alloy Wheels Direct, rimstyle, bmw-alloywheels and 1st Choice Spares.