"Best" and "Cheapest" don't go hand-in-hand.
Two options......
1) Get X-Rite i1Profiler....you can use your EyeOne Pro with it directly or you can use the Spectrolino/Spectroscan with the free ColorPort Utility to take measurements and import into i1Profiler.
2) Download the (free) X-Rite ColorPort Utility for creating and measuring your profiling charts for either of your spectros.....send the measurement data off to someone that offers a profiling service....it would take quite a few trips to the profiling service before it would pay you to get your own profiling software.
Regards,
Terry
Terence Wyse, WyseConsul
Color Management Consulting, G7 Certified Expert