A lot depends on the quality of the hay starting with the grasses it is made from, age at cutting etc. For really "good" hay £3 is very cheap. I sold last years hay at that price, it was nice hay, well got, from very old permanent pasture but while good for ponies and sheep it was not what would be classed as racehorse hay for which people were prepared to pay £5 a bale.
This year my already sold hay is £3.50 and I have a waiting list for another field which is down now.