Mine are even lower than your 25p e/w Tegan ! As I say, minimum deposit or top up is £10, and that lasts me ages! My account is currently standing at £19.78, and I only topped up when it went below 50p!
Friends have sometimes said "bet you wish you had put a fiver each way!" when I have had a long odds one come in, but I'm very happy with my 10p each way ones.
Excuse the pun, but it is horses for courses, and I would rather have a fair few at 10p e/w and enjoy the fun than a smaller number at even 50p e/w.
There are some that insist on more, Betfair for example,where I think it's a minimum of £1 e/w, could be wrong, but I'm happy with what I do.