The
Direction Compostelle shop mentioned above may have adequate hiking poles for purchase. They carry a lot of souvenirs and an assortment of basic items any pilgrim might need. On my first Camino I bought a trekking raincoat here that worked adequately for a month.
Another very good choice I recommend highly is the
Maya Sport shop located on the flats along Avenue du Jai Alai. Get a town map and search for the
Carrefour Supermarket. Maya Sport is located out on the main Avenue du Jai Alai.
It is maybe a good 10 minute walk from the center of town. Basically, walking back towards the train station, at the base of Rue de France, turn right onto Avenue du Trinquet, and follow that street to the roundabout. KSO onto Avenue du Jai Alai. Maya Sport and the Carrefour market are on your right.
This store is a slightly higher-end sports shop that caters more to the locals than to tourists and only-pilgrims. Hence, the quality is relatively better. They sell name-branded products, not 'made for the tourist trade.' However, the prices are the same, IMHO.
Here is a page describing this shop:
http://www.chemindecompostelle.com/mayasport/index.html
Here is the home page for the Maya Sport web site:
http://www.mayasport.fr/
Unfortunately, as of this writing, the page is under construction.
When you consider poles, beware of heavy, steel or cheap aluminium anti-shock poles. I advise against buying them. They are heavy, noisy and prone to breaking more easily than conventional twist fasten or toggle fasten poles. IMHO, the anti-shock feature is a useless gadget that sounds like a good idea but is not. They rattle with every step...very annoying. Most of them get tossed in the 'discard' box at the Pilgrim Office at Santiago, if they make it that far.
This said, when you DO find a pair of poles you like, please DO buy a pair of rubber tips to cover the tungsten steel pointy tips. It stops the annoying 'click-clack' sound these sticks make on paved surfaces...all across the
Camino Frances...for 800 Km! The tips are a standard 12mm interior diameter and are sold in most all sport shops along the Camino. They are very cheap in France and Spain.
Hope this all helps.