I don't think @snorkie635's 8-string is the more conventional setup - AFAICS most 8-strings have the octave string uppermost, as does my Dean 10-string. Also, as 4-string sets start at around £15-20, £40 for twice the number of strings seems OK. I can't remember exactly what I did, I think it was a five-string set (or possibly a 6-string set) and a number of single strings.