Actually, I may as well post the lot of the formulas that are killing me. Also,

=IF(B8="Sheet",'Materials Usage'!D51*('Rate Index'!$X$5/60)*Costs!$M$14,('Materials Usage'!D38/INDEX('Rate Index'!$B$3:$K$22,MATCH(Estimate!B37,'Rate Index'!$C$3:$C$22,0),MATCH(Estimate!B8,'Rate Index'!$B$4:$K4,0)))*Costs!$M$14)+INDEX('Roll Load Costs'!$N$2:$P$9,MATCH(Estimate!B37,'Roll Load Costs'!$N$2:$N$9,0),3)

=IF(Estimate!B8="Sheet",'Materials Usage'!D51*('Rate Index'!$X$5/60)*INDEX(Costs!$L$3:$M$27,MATCH(Estimate!B37,Costs!$L$3:$L$27,0),2),'Materials Usage'!D38/INDEX('Rate Index'!$B$3:$K$22,MATCH(Estimate!B37,'Rate Index'!$C$3:$C$22,0),MATCH(Estimate!B8,'Rate Index'!$B$4:$K$4,0))*INDEX(Costs!$L$3:$M$27,MATCH(Estimate!B37,Costs!$L$3:$L$27,0),2))

IF(INDEX('Rate Index'!$B$3:$K$22,MATCH(Estimate!B38,'Rate Index'!$C$3:$C$22,0),MATCH(Estimate!B8,'Rate Index'!$B$4:$K$4,0))=0,0,IF(Estimate!B8="Sheet",'Materials Usage'!D51*('Rate Index'!$X$5/60)*INDEX(Costs!$L$3:$M$27,MATCH(Estimate!B38,Costs!$L$3:$L$27,0),2),'Materials Usage'!D38/INDEX('Rate Index'!$B$3:$K$22,MATCH(Estimate!B38,'Rate Index'!$C$3:$C$22,0),MATCH(Estimate!B8,'Rate Index'!$B$4:$K$4,0))*INDEX(Costs!$L$3:$M$27,MATCH(Estimate!B38,Costs!$L$3:$L$27,0),2)))

Just these four... But they're all popping me back errors every time an index value is zero...