Hi Suzanne
I stayed in San Sebastian for a couple of days last year in a place called Pension Bergota which is near the harbour in the old town. Great location and very clean. It is one of the pensions which has a door at street level but the rooms and reception are up some stairs. They didnt serve breakfast but it was not a problem as plenty of cafes close by.
I have done an internet search to try to get you the address but can't find it and the word "bergota" is throwing up some some seedy references so either I have got the spelling wrong or there is a double meaning to the word that is not in my dictionary!!
I found the hotel in a brochure I got from the tourist information office and there were lots to chose from. I suggest you go there and pick up a copy if you can.The pension proprietor was happy to show me the room before I commited myself to taking it. I cant remember the price but it was one of the cheaper options that had a private bathroom.
I also went into the opulent 5 star Hotel Santa Monica to see if they did a special offer for pilgrims but nothing doing and I did feel decidedly out of place with my backpack and crumpled appearance! (Always worth a try!)
I found San Sebastain to be a delightful place, the beach is beautiful -especially after not seeing the sea for weeks. However it was by far the most expensive place I have stayed in Northern Spain. It was quite a shock to my purse after the prices on the camino and even in comparison to the cities like Burgos, Leon and Bilbao. For example, a couple of tapas cost as much, if not more, than a three course meal elsewhere. Anyway, dont let me spoil things for you. I am sure you will love it and even if the fish restaurants at the harbour are expensive the food is great and the views even better.
Good luck and buen camino!
Laura