Convertible Rules

Option 1.
The simplest easiest way, is to buy a bolt in roll bar. Autopower makes excellent roll bars. They make are variety of styles and designs, even colors too. They are fairly straight forward, and easy to install. You can do it yourself, and will need a drill and some basic wrenches and tools. Expect about 1-2 days to put one in. The time will vary on your car and you experience. Here some references for you. http://www.roadraceengineering.com

Option 2.
A pre-bent weld in roll cage. Autopower also offers this. This can be cheaper if you do the work yourself, but you will need an addition to the bolt in tools, add an arc welder, Sawsall, fish mouth bit, drill press, and somebody to put it all together. If you need to hire someone expect to pay about 2-3x the bolt in price for a full install. Remember your life depends on it, so choose someone you trust. The tubes come only bent but not welded or cut. So you have to measure cut and weld everything as you put it in. You can get a better fit and do a little customization that you can't do with a bolt in, but it's more time and possibly more money. Figure on a minimum of 2-3 days work for this one.

Option 3.
Full custom roll bar. This is the most expensive and hardest bar to make. You will need the same tools as a pre-bent kit. Expect a min of 5 days. Cost starts at around $2000 for a full cage. The good part is you can do some trick stuff, but be careful with who you have doing your engineering. The bar must conform to the NASA CC&R, or the SCCA GCR.

Stay away from the chrome vanity bars. Like the 4WD bars they will crush up really nice on a roll over.

My best advice is unless you have a need for some custom work, is go with the bolt in. It's cheap, simple, painted, welded, fits your car, and it's already been tested by others upside down drivers!