I posted this on the FM forums a few days ago, thought I'd re-post it here in its entirety:
I also agree with the John Shaw book, it's excellent. I'll try and answer your questions as best as possible.
1. Yes, anything in photography can be expensive. You don't need a MPE-65. How did I know you shoot Canon? You mentioned 1.6x crop, Nikon cameras are 1.5 crops. Plus Nikon doesn't have anything that even remotely touches Canon's excellent MPE-65.
In all honesty, I wouldn't recommend this lens to a newbie. My suggestion is to go for one of these babies:
a. Sigma 105mm
b. Canon 100mm
c. Tamron 90mm
The Sigma most probably will be the cheapest of the 3, but don't let that you fool you, it's an excellent lens. I would recommend a dedicated lens as it'll go 1:1 (ie. life size) and it'll be razor sharp.
2. Yes, you can get these normal lenses that have 'macro' written on them. Beware: they're not true Macro lenses, they usuall only go down to around 0.3:1 (ie. about a third life size), if that. Optically quality is usually not on par with a dedicated macro lens. Sure, you can add dioptre lenses onto the front of these babies to get more magnification, but again, beware: you'll lose optical quality.
If you want to start out, you could try a 50mm lens with a set of extension tubes, they'll give you 1:1 or even more, but the working distance from the insect will be much closer than a dedicated macro lens. And furthermore, you can't easily change magnifcations on the fly like you can with a dedicated macro lens, but instead have to remove or add tubes. They usually come in a set of 3, something like 12mm, 24mm and 36mm or thereabouts. Optical quality is excellent, as there's no glass involved.
3. As a general rule, most dedicated macro lenses will be only 1:1. Tubes (as an example Kenko) with a 50mm will give you around 1.8:1. The maths when using tubes is usually:
length of tubes/focal length of primary lens
ie 68/50, which works out to about 1.4:1. From experience, I know that these equations are only rough, and that magnifcation is best worked out using a ruler, hence myself saying that instead of it being 1.4:1, it's actually around 1.8:1 or so. Take a shot of the rule, and work out how many mm fill the frame. As an example, with a 1.6 crop camera, the 30D, the sensor measures 22.5mm wide by 15mm high. If you photograph a ruler, if the entire image takes up 22.5 you're shooting at 1:1. If you're shooting at higher magnifications than 1:1, simply use this to determine magnification:
sensor width/ruler coverage
Of course, Canon's MPE-65 is a zoomable macro, going from 1:1 to 5:1. You don't need these ultra high magnifcations imho. I personally feel that they spoil macro photography, by removing the Insect or Arachnid from its surroundings. That's just a personal viewpoint, each to their own.
From 1:1 to 2:1 you can handheld, it does take a lot of practice, but it can be done. Higher magnifcations are much more difficult due to magnified camera shake and a much dimmer viewfinder image.
Oh, I forgot reversed lenses. It's quite common to use a reversed 50mm. You can either handhold the 50mm lens in front of the camera mount (not really recommended) or buy adaptors that allow you to mount it onto the camera mount. Ebay has lots of sellers selling them. You'll get reasonably good magnifcation and optical quality, the drawbacks will include vignetting in the corners, and complete loss of f stop control on the lens being reversed. Plus, the rear element of the lens is open to the elements. For these reasons, it's a good idea to buy an el cheapo 2nd hand 50mm - it doesn't matter what brand. Nikon f1.8 or Pentax SMC 1.8 50mm lenses are good options optically. You can also mount the reversed 50mm onto another lens using the same method of an adaptor to get more magnification, you'll experience some drop in optical quality.
There are also things such as bellows, that give you a working range of magnifications, but in all honesty they're more trouble than they're worth, and you'll almost certainly have to use a tripod.
In all honesty, go for something like a Sigma 105mm, you'll get 1:1, a good working distance (so as not to spook the insect or spider), and excellent optical quality, as well as the ability to change very easily your magnifications.
Hope this helps.