Do you sell replacement inside handle 800-2 only for patio door?

Sorry, we don't have inside handle only for replacement, but we have many whole handle kits:

With key lock: SK800KBL

Without key lock: PD800ACL, PD800ACR, PD800E7390L, PD800E7390R, PD800AML, PD800AMR  

Check them out here: https://www.idealinc.com/en/door-and-window-hardware/patio-doors-windows/handles/

We have the outside handle only without key lock as replacement model 851-1E3969:

https://www.idealinc.com/en/door-and-window-hardware/patio-doors-windows/handles/851-1e3969-851-pd-non-locking-exterior-handle-white-sk-pd800

For the outside handle with key lock only, check out the SK801 here:

https://www.idealinc.com/en/door-and-window-hardware/patio-doors-windows/handles/sk801-discontinued-surface-mount-locking-unit-white-sk800kbl