[Oskatat]

if he's being selfish, rally the other players to be so too. As long as the cleric (or other healer) is not under a compulsion by his faith to heal everyone who asks for it, he can keep healing from those who don't deserve it. If that works, he just lost the support of 2 powerfull spellcasters

the "i dont help you in combat" card works even better if the cleric agrees to side with you

a very symbolic (and lawfull) way of showing your displeasure would be to say "if we dont get anything, you wont either" and destroy some loot. Harsh, and goes against D&D instincts, but it gets the message through i'd guess

next time he does attack you, just tell him something like this: "lay hands on me again and I'll blast your sorry hide to bits". he knows you can do it, your allignment perfectly allows that and he cant kill you without betraying his allignment... if he does and the DM allows it, find a new group

lastly, if he is allowed to use his superior combat skills to take items from you, you are allowed to use your superior magical skills on him. hold person/monster has been mentioned, as well as charm. balefull polymorph might be a bit extreme, but you can polymorph yourself into a giant and start a grapple. grab the loot and cast greater invisibility on yourself. "suggestion" him to hand over some items. dominate spell would work too... or trap him in a resilient sphere, or hide there yourself. and these are only the friendly options. bestow curse is very nasty.