It must be kept in mind that large price variations can be expected based on a multitude of factors such as the following:

Availability
This is always the most important price determinant - Supply and demand - certain specimens within a group may be very rare or thought to be rare and can command much higher prices than more common group members.
Size and Form
Larger pieces may cost less per gram as a result of less cutting waste and preparation, while broken fragments are often less expensive than cut slices. Remnant fusion crust is usually considered a premium. The slice thickness is also an important price determinant, again due to cutting losses.
Weathering
Meteorites that are seen to fall can be recovered in fresh condition, while those that are found may be extremely old and weathered. Fresh and/or cool looking meteorites are in higher demand.
Preparation
Great price variation can exist due to the quality of cutting, polishing, etching, and presentation, as well as to overall customer service.
Historical Interest
The demand side of "supply and demand" can be greatly influenced if the specimen was seen to fall, hit something man made(car, house, curb?...), came from an identifiable celestial object, is historically significant, or just effectively hyped by the seller.
What's in a name?
As a general rule meteorites with names hold their value better than meteorites from Africa with just a number.
 

If you just want to own a meteorite, very nice classified pieces can be found for under 25 cents per gram on Ebay.

You can also find unclassified meteorites mostly from North West Africa (NWA) for under 5 cents per gram on Ebay.

Caveat Emptor, and Good Luck!

METEORITE PRICE GUIDE - August 2007