What other cost-saving options are there?

One option is to go with Rambam ratio using Raavad strings, thereby making two sets. To quote R’ Avi Grossman:

“… you can buy a set of four, full length, Raavad style strings, then cut each in half, and join those eight halves with ordinary strings, and then you’ll have enough techeleth for two garments!”

Technically speaking, from the above chart, compare Raavad Chinuch/GR”A regular length versus Rambam 7 regular length, minus a little bit as Raavad uses 6 Techeiles chulyot. Raavad Chinuch/GR”A gives you 49 inches. Rambam 7 gives you 24.5″ Tekhelet. 49″/2 is 24.5″. Even if you factor in one additional inch from tying the two strands together, you should still be good. Raavad full is a bit more expensive but at 70″ Techeiles gives you a lot more to work with.

Ordinary strings would need to be purchased separately, but if you would like two pairs of Tzitzit tied we can work out an arrangement. In addition, cutting would only be done using plastic, wooden or ceramic scissors, to satisfy the Mishna Berura who writes “one should cut with his teeth and not with a knife” (MB 11:61) – see here. The general idea is that metal traditionally was used for implements of war and bloodshed, which should be avoided if possible. As an aside, bedieved, the strings cut with metal are 100% kosher.

Here’s a visual how it would look with GR”A strings (would work with Chinuch and Raavad tying as well).