A pound week...why,she could almost pay that out of her hous

是a pound a week,文章背景是她在一个商店看到了一个armchair,原话是,There was a card on the chair which said:"This fine chair is yours for less than a pound a week,"and very small at the bottom,"Cash price eighty-nine pounds fifty." A pound a week...why,she could almost pay that out of her housekeeping money and never miss it!
why 有感叹词的意思,根据这句话后面的感叹号,应该是对这个价格表示惊奇的意思,所以选择why
不过我对she could almost pay that out of her housekeeping money and never miss it这句话也不是很理解,是说她完全有能力支付还是什么呢?谁帮忙具体翻译一下~