El Sadar Stadium is a venue in or near Pamplona that is most often used for Soccer
They may be a small team, but tickets still go for anywhere from €20-65 euros, depending on the quality of opposition and the view. This is La Liga after all! If your seats place you behind one of the goals then you're looking at the cheaper seats, and adding €30-40 euros to that price as you navigate round to a central position overlooking the whole field. The stadium isn't the prettiest in the country, but the seats have decent legroom and it more than gets the job done!
The El Sadar stadium is not very big (it can hold around 18,000 spectators), so the visibility is good in general from any stand. However, main stand ("Tribuna Preferencia”) is in my opinion the best one. Ticket prices vary depending on the rival and the type of the game. If Osasuna plays against Real Madrid prices can be between 40-90 euro.