Bad luck. Both Kiteworld and Go Kites have 3wrap spars £18 for centre and £17 for outer.
Always check the ferrules in the centre so that they do not come loose and start to move. If a ferrule moves then the joint becomes a weak point and breakage can happen. You might consider buying a complete set as they come in slightly cheaper than 5 individual spars and you would have spares. Also note that the EXP spars are 3 wrap and £1 each cheaper at Kiteworld, they are the same size as 1.5 spars just marked differently.
You said the kite was an SLE from a few years back. Are you using the SLE leading edge which is wider diameter tube than the vertical spars and the end caps fit inside the spar. If so there should be a large washer fitted on each end cap to protect the bungee from being damaged by the spar end. If that is where the damage is then "go kites" can supply you with spares available on their eBay shop and are in stock. The damage could be broken washers or damaged bungees caused by missing washers on a SLE shaft.
If you do not have SLE spars but standard 1/4 inch spars they also have 3 wrap centre and vertical spars available.
If you need more help a bit of elaboration on "broke both tips" would be helpful.