Not that good at translating but,
「いやーこれは買うしかないっしょ」would roughly translate to "Well, it seems like we have no choice but to buy this one",
「なにこの価格破壊」-> "What's with these prices?"
「決まってんなら俺いらなくね?」 -> "If you have already decided then there's no need for me, right?"
「い"ゆ"く付き?」- I don't understand...