On average, expect a Honda Accord V6 turbo kit to cost somewhere between $3,000 and $6,000, but the exact cost will depend on what the kit includes, the quality of the kit, etc.
Slick Fab LLC, for example, sells a 2013 - 2017 Honda Accord V6 Turbo Kit for approximately $5,000—it includes a 6266 turbocharger, turbo and engine wastegate, 500hp rated front mount intercooler, custom fabricated intercooler piping, genuine FIC 775cc injectors, and more.
If you want something a little cheaper, consider purchasing Vivid Racing’s Turbo Specialties T25 Extreme Turbo Kit Honda Accord F20B | F22B 98-02—it only sells for about $3,000.