So I just did a test myself (I didn't buy the hireling... used a friend's )
I did 33 dishes: So I spent 495k in total (+900TC if I had bought the NPC, but lets forget about it).
Only made to do 7 dishes to raise mana, and 6 of hp (30% each): So every one of these would be 38k
So far 'pot of blackjack': which is over 300-400k on my server, can be used 3 times and heals me almost completely, is way better and cheaper than the hp one.
So... conclusions: I'm not buying it. You will probably profit with them if you are continuously in war, and even then I doubt any of them would save you from dying.
I really would only buy it among a full guild or a group of friends. Otherwise I really think it is over overrated.