If Tormentor Titans are slightly too expensive, then Vessels of Pain are great alternatives. At only half the prize they come quite affordable, yet not worse armed. Two TK weapons, a blast weapon and a few more shots grant you a formidable load out. In engagements though they tend to not deal enough damage on their own, even with supporting fire. If that is what you want them to do I would strongly recommend, taking them as upgrade for Flotillas or taking one formation of two for 500 points. This also increases the efficiency of the blast weapon to two templates with higher impact on enemy formations. The models themselves required very little conversion as you can see. I put them on slightly larger flying bases to get a good mix of blue and red on these models.
Do you have models for VoP as well? If so, post a link in the comments below.