Interesting question. Depends on what you are doing. Having just gotten into it, those spools will last you quite a while. Once you progress to more complex builds, if that's where you want to go, you will see your supplies dwindle quite quickly.
I worked it out the other day now that I'm selling sets of my Framed Staple builds at the local B&M and wanted to know how much each was costing me in wire and to start to plan when I will need to order more. They are made out of 8 strips of 0.4mm x 0.1mm ribbon for the core, framed with 28 AWG, and wrapped in 36 AWG. All are Kanthal, and all come from Lightning Vapes. One set of those coils consists of 2 4.5 inch lengths. Works out to 6 ft of ribbon for the core, 1.5 ft of 28 for the frames, and 20 ft of 36 for the outer wrap.