I'd see if you can get 1 bottle from somewhere to try out first. My son hated them, and I struggled to figure out exactly how they were "closer to nature" when the teat was practically solid (compared with out NUK bottle which he likes) and also to get the last ounce out, you have to lie baby practically on their back cos the teat is so wide.
thats out experience with TT, also the steriliser was crap, lid didn't fit - leaves water in the bottom afterwards.....and breast pump was crap, i got twice as much out in half the time with a £15 Avent hand pump :/
Ebay is probably your best bet, or maybe amazon but i havnt found baby stuff on amazon to be much cheaper than the shops and also im impatient so would rather spend the extra quid in the shop to have the thing "now" lol!!!
ANYway im not telling you not to buy TT stuff, but just recommending trialling one to see if LO takes to it or not xx