It's fine, I got a brand new Avent 3 in 1 sterilizer that was only used once or twice off ebay for 10 quid and they go for so much more than that in the shops! You actually don't have to sterilize things more than once, but people do anyways and I will be to be extra safe because I plan on pumping and don't want any chances with bacteria on my pump causing me to get mastitis or anything scary like that. Some people go OTT with sterilizing though, and I don't honestly know why they go through all the trouble doing it so much. Tap water is safe and sanitary unlike the old days when sterilization was a big deal, now a days washing with hot soapy water or running through the dishwasher is more than sufficient and sterilizing isn't really all that big of a deal but it's good to do it once in a while to be extra safe. You don't even need a sterilizer to be fair, boiling on the stove for 5 minutes or putting boiling kettle water in a clean bowl or container with your equipment and bottles in it is fine. They also sell cold sterile tablets that you just drop in water and let the stuff soak in for a while. Steam ones get limescale sometimes so you might need to grab some inexpensive treatment stuff to put in it so it doesn't build up.