Maybe I can give some advise for those who have issues with collecting 250 blood coins. There are possibilities to open them a lot cheaper.

If you play MK11 and open some chests you have a chance to earn a lock pit or sindel's ring. The lock pit let you open any chest without spending the amount of coins (blood or gold). If you use this in front of a blood chest, you have to spend 0! coins.

Sindel's ring reduce the cost around 50%. So you only pay 125 blood coins instead of 250. This "buff" lasts 1 minute. If you use it wisely you can open two blood chests for around 250.

I hope this helps you a little bit to gain the treasures faster. Another little advise... don't use consumables for a tower which let you earn more blood coins for each performed fatality/brutality. Maybe NRS is patching the amount of blood coins you can earn per fatality/brutality, then you could be glad to have some consumables like this with you :)