I recently returned from Spain. I did a loop Madrid-Sevilla-Barcelona-Santander-Madrid in about 11-days. Here's what it cost me (in pesetas) with no railpass:
Madrid-Sevilla: AVE (turista-llano) 10.100
Sevilla-Barcelona: all-Preferente Talgo Hotel Tren 20.100
Barcelona-Santander: (ViaCarsa Bus) 6.250
Santander-Madrid: (Continental-Auto bus) 3.400
Total ESP 39.850
less than $250 USD
The Hotel Tren cost more because it was individual occupancy in a compartment with two-beds.
If I had a railpass I would have had to pay a supplement for the AVE and the sleeping compartment on the hotel train (ESP 10.000).
The Hotel Tren is an all-Preferente Talgo.
I provide this info just in case anyone out there is comparing prices to see if a railpass is justified. I was not eligible for a youth discount or for the discount you get for 2-people traveling together. For me point to point was the most convenient and economical way to go. Note that I used buses on the Barcelona-Santander and Santander-Madrid segments. I also used buses extensively in Andalucia and Cantabria. For convenience sake I rode the FEVE (Ferrocaril español de via estrecha) Santander-Limpias (I returned by bus: Limpias-Laredo and Laredo-Santander). That way I arrived Limpias (around 10:15), visited the Church where Cristo de Limpias is, walked back down the hill to the crossroads and caught the 12:20 bus to Laredo.