If you replace your roof and reuse old gutters, you've thrown away the cleanest install window you'll ever have. We strongly recommend new gutters at the same time as a roof replacement — single crew, single trip, single warranty, perfect alignment with new drip edge.
5″ seamless aluminum: typically $9–$14 per linear foot installed. 6″: $11–$17. Add ~$8–$12 per linear foot for micro-mesh leaf protection. Drone-measured estimate in 24 hours.