The easest solution would be for dead pets to have a timer like the talismans.
Say, an 1800 second timer.
While the timer is running, ONLY other PCs can rez your pet. Personally dying or losing connection would reset the timer to 1800 seconds.
AFTER the half-hour is up (since the pet last died, you last died, or you last disconnected, whichever came last), THEN you could pay the Britain NPC pet to rez.
Cost would be half the purchase cost, if something buyable.
For tames of a type not buyable from an NPC, cost would be 50 times the pet's current barding difficulty (note this goes up as pet is trained up), times the control slots of the pets (so a pet taking 3 control slots, with a barding difficulty of 60.0, would be 50 x 60.0 x 3 = 3000 x 3 = 9000 to rez).
Of course, this would mean that a lazy tamer would have to pay something like 35k gold to get a Greater dragon rezzed, and would still have to wait a half-hour for it - if one would even allow pets over 3 slots to be rezzed by an NPC at all (which, frankly, I wouldn't allow).