Is asacol 5-asa?
5-ASA's include Sulfasalazine, Asacol, Colazal (Balsalazide) and Pentasa. They are also available as rectal meds - enemas and suppositories. They can be very effective, but if your budget is limited, they're a bit pricier than either Imuran or Pred. But many fewer side effects.
I did miss in your signature that you're taking Asacol, sorry. Do consider the rectal meds, though.