Does anyone have any thoughts on buying bottles secondhand? I found someone selling 12 9-oz Tommee Tippee Closer to Nature bottles (the same ones I registered for) for only $40. Typically I've seen them for $15-20 for 3. This sounds like a great deal to me, but should I go for it? Any concerns with buying secondhand bottles? I will, of course, sterilize them before use.