A fortune is a debatable term
For macro lenses it partly depends on what you intend to shoot with it. This is because of the working distance of the lens - which is the distance from the subject to the front of the lens itself (which is different from the minimum focusing distance which is from subject to the camera sensor). Essentially the longer the focal length of the lens the longer the minimum focusing distance and thus the more working distance you will have to work with - this is of importance when working with subjects such as insects where the closer you get the more chance there is of spooking the insect; whislt for static subjects distance really has very little effect since its not going to run off.
Another important point is that when working at full magnifcation (that is 1:1) a 60mm macro lens and a 180mm macro lens will give you the very same framing of the shot - you won't get any more or any less zoom with either lens. Of course when you focus on further off subjects you will of course see the difference between the two focal lengths.
In addition the macro prime lenses on the market are all very equally placed image quality wise, so there really is no macro lens which is "Sharper" than all the others. Though studio tests might be able to rank the lenses in some order, outside of totally controled conditions differences in sharpness will be far more based on correct shooting style and lighting than the inherant sharpness of the lens.
lenses on offer include:
Nikon 60mm macro - a good short focal length macro lens and a good option for budget and working with static subjects (edit - it is fullframe compatable as well in both its D and G versions - I have no idea what D and G mean though - sorry)
Tamron 60mm macro - a newer 60mm offering and a very strong choice since it not only has inner focusing (the lens does not extend as you focus it, all movement occurs inside it) but this lens also offers an increased working distance - similar to that of a 100mm macro lens. It is however, only crop sensor camera compatable*
Sigma 70mm macro - the shortest offering which is fullframe compatable - again its a strong choice. It also has the added bonus that it will work with both the sigma 1.4 and 2*Teleconverters; I have this lens and have used both teleconverters without any forcing needed when attaching them (even though it is not listed as such on the sigma website).
Tamron 90mm macro - a very popular budget choice macro lens (budget because its cheaper than canon and nikon 100mm offerings) and is the shortest recomended focal length macro lens for insect work.
Sigma 105mm macro - another offering from sigma and this lens is very similar in its build and AF to that of the 70mm macro from sigma. It is however not compatable with the teleconverters.
Nikon 105mm macro - One of only two lenses in the macro ranges which has stablization (VR for nikon) which although it only gives a reduced effect at macro distances, is still very much worth having in a lens.
Sigma 150mm macro - this lens and the 180mm sigma are a cut above the other sigma offerings in build and AF quailty (optical quality remains very similar - as with all macro lenses). These two lenses offer HSM focusing (which makes for faster, noticably quieter auto focus as well as all the time manual focus); the inner focusing feature and are also compatable with sigma teleconverters. The 150mm is generally the more popular choice with people aiming for handholding the majority of the time.
Sigma 180mm macro - features the same as the 150mm but with a longer focal length - its often the prefered choice of those who work more from tripod than handholding -but is still fully handholdable.
Tamron 180mm macro - oddly an unpopular macro lens, I have seen very few people using this lens (only a handfull at most) and it tends to lose out to the more popular sigma 180mm macro - even though its sharpness is still in line with the other macro lenses
Nikon 200mm macro - I have little to no understanding of this macro lens (I'm a canon shooter) but I am lead to belive that it is a macro lens in good standing - but I have no ideas as to features after that - like the Tamron 180mm I have not seen many users of this lens.