Well you may already have gathered that the folks behind this Company were originally behind Vueling, which is not renowned for rewarding it's First Officers (assuming it is that for which you applied) with a decent salary.
And the first base, rather than in Spain, is to be Venice in a country therefore which is not renowned for rewarding LCC First Officers with a decent salary (think Windjet/Blue Panorama).
I have no inside knowledge but could draw my own conclusions.
Bearing in mind that they are only seeking people with upwards of 1500 hours (i.e. not 200 hours wallet-wavers) I would be inclined to decline their kind invitation until such time as they either reveal the basic employment terms offered or waive the assessment fee.
And if everyone would do this you can bet they would soon change the requirements for attendance.
Anyway, 460 euros to attend is a downright disgrace.