i didnt buy one, but had some problems while bfing (oversupply) so i had to express for comfort, my best friend had a hand pump that she never used, and lent it to me, now i express every night (if i dont do it after the last feed of the day, i wake up with massive sore bbies) and that way i have a small supply if i need to leave her with someone (MIL or DH)
i wouldnt buy one incase u never find the use for one, and if you do end up needing one you can just go buy one.