CRC currently has the sram Narrow Wide Steel Chainring at £9.99.

Would this ring work with my slx triple cranks in a 1x set up?

Afaik the SRAM rings have a different BCD that wouldn’t fit.

as above, the x-sync will be a 94mm BCD

the slx is 96mm though?

slx I’ve seen are 104 bcd

most slx triple are 104, but there is one with 96.. but it’s still not the 94 of SRAM rings.

I’ve just ordered one of these for SLX cranks – http://www.wolftoothcomponents.com/collections/stainless-steel/products/104-bcd-stainless-steel-chainrings. Not Sram prices (which are stamped steel not forged and hardened stainless) but it should last for approximately 3 squillion years. Or not but certainly many times as long as alu chainrings that cost more than half the amount. Bikeavenue.de is doing them cheap at the moment; high delivery cost but still bargainous.