Arc flash relays are quite expensive and as a cut price alternative you could consider temporarily switching the instantaneous setting of the standard protection relay on (if it has one).
The down side to this is unlike arc relays it won't be permenantly on and it would be at risk from tripping if big loads are switched on whilst it is activated.
Although not quite as fast, the effect of instantaneous protection is comparable to an arc protection system.
Arcaware has practical experience of the Vamp system and Micom relays and can positively vouch for their functionality and reliability. Arcaware has no practical experience of any of the other systems.