hi, i've been through this recently http://www.xt660.com/showthread.php?t=17351 have you priced the nessasary components? as yamaha parts are quite good value, yes i can understand labour rates have to be factored in as well.
as for will a r or x fit, i would be suprised if they didn't, give the guru Kev a shout. what he dont know about xt's aint worth knowing!

good luck with you repair

ps good idea to subscribe! will save you a fortune imho