You can grow
sps corals with T5's, although it is recommended to get the individual reflectors for the bulbs. You can look at the thread The VZ Reef for a very good example of what can be accomplished with T5 lighting.
Do you have a canopy and DIY skills that you can use to build the lights into it? That would be your cheapest way to go. If not, then you are like me and basically forced to buy a pre-built fixture.
You have already seen that the fixtures are pretty pricey. My recommendation would be to check the classifieds section on this forum, Craigs List for your area, and any other sales areas you might now of, for a used fixture. There always seems to be someone getting out of the hobby and if you are patient you can get a really good deal on a fixture you never thought you could afford.
On the other hand, if money was no object then I would want to look at the Solaris LED fixtures as they add no heat to the tank, are fully programmable, and only use a fraction of the electricity. The bulbs are also supposed to last more than 11 years which is something else to consider in the long term cost of your lighting.
If you want to see the Solaris in action, check out the thread Bittner's Salty Madness.
HTH