I tried a few places, tack shops, village notice boards, local post office, facebook etc but in the end I had all my interest from preloved. It took a while to find someone suitable though (6 months), even for two lovely natured and quality ponies.
We are lucky in the East Midlands that we have the AdMag - i know it is for selling but you could maybe put a Share advert in there.. This will reach only local people instead of the rest of the UK aswell...
But apart from the AdMag i would say;
-local feed shops/tack shops.
-preloved(one step ahead of me there but I LOVE this site for ads!)
-try the forums - this is an east midlands forum after all, so again, you would be reaching local people.... Its a way to actually speak to someone aswell without them just ringing up like they would from an ad!
x