You need not go far; just outside the Church is a line of food stalls, fruit stands, and handicrafts stores.
What to buy: Rattan handicrafts from Pozzorubio; tropical fruits (mangoes, chicos,guavas,etc); native delicacies ("Tupig", Ilocos chichacorn, Calasiao "Puto",etc)
What to pay: Your P100 will go a long way; you'll have lots of fruits/delicacies already.
The Manaoag Church's Religious Stores (there are 2) have all kinds of souvenir and religious items - keychains, car decor, fans, t-shirts, hats, stampitas, novenas and statues/wall hangings of Our Lady of Manaoag, calendars, posters, candles, Holy Water bottles, etc. There are other religious icons/articles for sale at very reasonable prices, absolutely cheaper than those offered by religious stores outside and ambulant vendors.
What to buy: Almost all religious articles you can think of may be found at the Church Religious Stores.
What to pay: For P100 or less, you'll be able to buy many novenas and/or religious articles for keepsake or give-away.