Paul
I would very much agree with Chris. Basically Victory Medals to non-casualty corps members such as ASC, RE and RA tend to be the cheapest, followed by Line Regiments, then Militia, then unusual colonial units. $25 would be expensive for an other rank ASC, however double that would not be bad for some of the militia units. Again casualties will be higher, A first day of the Somme KIA would be well over $100. If you are seriously interested in WWI medals it would be well worth investing in Gordon Williamson "The Great War Medal Collector's Companion" . Should be easy enough to find one basically gives you all the info you ever needed to Know on WWI campaign medals and would probably more than pay for itself over a couple of years. You must not however show any interest in Indian Army medals to unusual trades , ranks or units, they are all reserved for me.
Paul