If you're really low on funds you can use liquidate (stat) in Aura's special skill menu. That said, if you're playing on normal difficulty it's quite possible that 500 perkia is more than you need as long as you use it sparingly on healing and focus on finding a consistent tactic for the fight.
I did try fighting for a good tactic but my party died. Couldn't deal with those one shot kills.
I exchanged gold for perika, with 500 perika I can only heal once, use attack all and counter once.
I have all the martial and magic skills possible before this festival, I farmed everything before starting. I have even completely cleared that forest of ruins, bandit hideout, northern cave.
Spells like brittle, water spell, thunder, light, fire, heatup, wind spell, martial skills like offensive, defensive, seductive stance, pierce, slash, etc.
Well anyway, I started again from my save and have cleared it.
Thanks a lot for replying.