Most states allow vehicles to be driven without tags for a short period of time with only a bill of sale. Possible for the buyer to also get his own temp tag before he leaves his home state.
If the buyer wants you to renew the tags, I would let him pay for it.
2012 RAM 3500 Laramie Longhorn DRW CC 4x4 Max Tow, Cummins HO, 60 gallon RDS aux fuel tank, Reese 18k Elite hitch
2003 Dodge Ram 3500 QC SB 4x4 Cummins HO NV5600 with Smarty JR, Jacobs EB (sold)
2002 Gulf Stream Sea Hawk 29FRB with Honda EV6010