I am looking for some energy-efficient electric heaters for a new room. Anybody know of any reasonably priced ones that really do work and won't run me up a huge electricity bill?

My mother has a log cabin at the end of her garden that she uses for work and she has 2 DeLonghi Rapido Oil-filled Radiators which she swears by, they are very economical and she is never cold! these are available from good old argos, Catalogue number:4157382. but you may be able to get cheaper elsewhere. they are also available in other sizes, This brand are very economical and reliable!!