Hello from SoCal - couple of questions

[Bassplayer]

I have a couple of Omega Seamasters, a gold vintage accutron, and a gold vintage hamilton and am about to take the leap into the Rolex family and would like to know if anyone can recommend a reputable dealer of pre-owned.

I am torn between the TT GMT II and TT Blue Sub. Also, is there anything that I should look out for - like bad year, etc.. Budget is capped at $5,200

Anyone buy on ebay? Seems a little risky to me.

Thanks in advance...