Traveling solo, young, fit granny, free-lance food writer, joining RS Basque tour late in May. Arriving 4-5 days before to do some stuff on my own, incl. cooking class that I booked. Checked RS pension recommendations, but looking for add'l suggestions, under 70E. On the edge of Old Town OK, but not necessarily deep in the noisier part of Old Town (but I'll consider these also). Personal insights appreciated.
This place is at your max price range but really worth it IMO. Only a few years old, awesome pillowtop mattress, very clean, quiet location in old town away from the bars. You might be able to choose your room based on preference of feng shui. Owner and his wife run it and love to make recommendations--the lobby wallpaper is a huge map of the city to make it easy to show locations. On second floor with no lift but he will offer to carry up your bag. http://pensioniturriza.com/web/
I spent a couple nights in the Pension Donostiarra in the late 1990s and, seeing from their website, the lady owner (a bit "brusk") is the same. It's located near the Buen Pastor Cathedral and is 6 blocks outside of the old part - La Parte Vieja, and about 4 blocks from the bay/beach's edge. Seems a single room in their low season - seemingly when you'll be there - costs 42 Euros. The rooms are/were basic, but comfortable and clean. San Sebastian-Donostia has A LOT of pensions. I'm sure you'll find the city beautiful, very picturesque on the bay, and - the best - the (sea)food among the best in Spain. Enjoy!! Saludos, MadridMan - AND BarcelonaMan - @ you-know-where!