I get samples from Animal Magic Pet supplies for Spenser. They have a thread in fundraising just now that you should check out! Their sample bags are a decent size and some can be bought individually. I have an order in for 4 bags just now (postage for 4 is the same as for 1). Spenser seems to favour the oat hays, but they are quite broad strands. I would just pick 4 different ones, and hope that Poppy noms what Casper doesn't like.