Defi are definitely the top of the line and a perfect match to the STi cluster, no doubt about it, but you do have other options.
Both Maddad and Prosport make gauges that are a very close match to the STi cluster and peform the same opening sweep of the needle that the Defis do. I actually just ordered a set of the new Prosport Premiums (boost, egt, oil temp - all electric) and a triple center pod, all for around 300 bucks.