I think the Vueling (
http://www.vueling.com) from Split to Asturias/Oviedo would be the best. Both for the price and time constraints. For example:
- plane Split - Oviedo on 15.08. (1 stop in Barcelona) 09:25 - 14:15 = 218€,
- train (
http://www.renfe.com) Oviedo - Leon on 15.08. at 17:49 - 19:59 = 20€,
- vou can stay overnight in Leon, which I would recommend (or in Oviedo and proceed on 16.08.)
- train Leon - Astorga on 16.08. at 07:13 - 07:49 = 5€
- and you start walking early in the morning,
- plane SdC - Split on 27.08. (1 stop in BCN) 22:10 - 08:50 on 28.08. = 153€ (cheapest in August).
- that makes together =
396€
- this would give you at most 12 full days of walking.
Connection Split - SdC (and back) with transfer to Astorga will be at cheapest option for ca.14 days approximately
425€, but you wouldn't be able to start walking until 13:00.
Connection via Madrid on 01.08. (and return on 14.08., actually on 15th in the morning in Split) and night train to Astorga (22:30 - 03:43) would be
418€.
Hope something of that would be helpfull.
PM me your E-mail and I'll send you some more info in Croatian
Ultreia!