ah photo useage , sale and rights a very intresting and touchy subject.
Im not a professional but i do alot of items in this area as i have sold a fair number of photos in the past 2 years with the camps i help with and other photos in my collection.
first thing to remember is that is that you never give away a photo no matter how in significiant you think it is because it sets a precedent in the future that they can use you for very cheap because of your past, this means even if its a tag line, or a small amount will keep the deal, but also remember to get a written agreement that this is a onetime use of the image (or for a certain amount of time , for the web) and that you still retain the copyright of the image. That if in the future more images are needed they must contact you to arrange that. the reason you need to write this out is that i have had people who bought prints from me who thought that once they bought the image that they owned it and could do what ever they wanted including copies, which isnt correct because on the back of the photo i had stamped copyrighted image, for reprints contact XXX for permission. this lady said that wasnt fair, and my comment to her was that she should have read the fine print on the order form before buying it. this is just one example of how not stating the boundries that people can twist them for there own use
Now for prints, the prices i have charged have varied depending on the subject and number of photos being bought. but on average im around $4-6 for 4x6 , ~ $8 for 5x7, and $20 for 8x10, but those are subject to change.
now if its a magazine that is asking for useage of your photo it is a totally different ballgame in that there are general standards already in place.
i use this tool to calculate the rate
http://www.editorialphoto.com/contracts/estimatorweb.html , because thats a realm where the company will try to get you for a cheap as possible, and thats why i use the tool listed above.
now its a little complicated but if you know the info you need to input in the input fields it will calulate it for you. for example if say rodales wanted a cover shot for the cover of a issue based off there 185k subscribers and almost 17k full page ad rate for a cover photo you would negotate for 1500 for the right to use that photo for the cover(but note this is for only the cover thinking like web useage or prints) for that issue only with no reprints. and web site useage is a different issue and pricing to.
i have mentioned copyright here several times, and this is the rights that you the photographer have for taking the image in the first place, now if you need to protect the image beyond that for legal reasons you have to register it with the US patent and copyright office(this would be mainly if someone has stolen your image and is claiming it as there own). Now if you come across the rare time that someone wants to completely buy out the photo you really have to think about how much this image is really worth to you and how much you stand to lose in future sales needsto be calculated into the price , but for most of use here i would outright sell a image for 5-25k this may seem high but its a very realistic price for a image and will weed out alot of the non serious types(for professionals this would be much higher)
but if you look online you will find various pricing guides and reccomendations.
as this is a real complicated subject if you have any specific questions post them or PM me and i will try to answer it as best as i can
I hope i didnt confuse anybody, but if you need clairification please ask
Tooth