A company called reaper miniatures have a large amount of "wizard" models which i have bought and can safely say are the correct scale for lotr, go on eBay and type in reaper miniatures, you will surely find a large catalog of miniatures, many of which make perfect wizards (there is also the GW elven stormcaller model), as far as stats go, i suggest using an elven stormcallers statistics, when you want to house rule the wizards into better models, i believe there is a fan made supplement on this site which lists the possible stats of each wizard, except they are evil, but if you are using made up rules it doesn't matter if you decide to use them in good armies
