I have had the quests (silver, bronze and gold shoe horses) for some time, too.
I also had some problems collecting the stuffs needed as they didn't drop as often as nowadays (after the update).
I realized that the only way to finish the quest is to charge 2 collections & 1 artifact. The first thing I did was trading for horses & items needed in coll# 28. Futark runes are really hard to find (I have never find it myself really) so what I tried to find is someone who has enough to trade it with your collection item. A friend helped me in getting the quest done, lucky me.
After you finished the silver & bronze shoe horses quests, you'll need to collect gold ones. What I did was trading the shoe horses with gypsies with turtle on. That way I got enough horses to charge another set of silver ones to trade with the gypsies. Finding the gypsies are harder than getting the horses unfortunately.
When you got all items to charge the hand of midas, you get gold shoe horses needed for the quest. I didn't use a single diamond to get them. It's social game, so go search the collections of your friends, left some tips, wake their helpers up, see if they have enough of something you need, and ask them to trade with items they might need.