I need an afforable macro lens - Advice Please

[Sheiky]

Yep, and they work too! Here's a couple of shots with the Kenko tubes on my 70-200mm f/4L IS and 40D (from a while back).

I bought a set of extension tubes myself as well. They are definitely not as handy as a dedicated macro-lens, because you lose pretty much all of your focus range. This means that the area you can focus on is very small. Not that bad if you have found your subject, but if you need to quickly focus on something it might be hard.
However the good part is that they do work very well. Combined I have 65mm of extension tube and it works great on my girlfriends 85mm, but I also really like it on my 70-200 F4L IS. And you keep the IS 'm not sure what magnification it gives exactly, but it's pretty nice. For the 85 and 70-200 you also keep a nice working distance. I tried it on my 50mm prime and 24-105, but those weren't good. Quite nice magnification, but so little owrking distance that it wasn't really usable in the field.

[Lars]

I don't want to make things more difficult, but the Tamron 90mm macro always gets good reviews. The IQ is good, and in the comparisons I have read, it beats Sigma, but as is the case with most Tamron lenses, the autofocus is rather slow. So if you are hunting bugs, I guess it is out of the question. Also, no IS. But it considered a good buy, due to its low price and high IQ.

Lars