Just for those wondering, the new gate (amber phantom, i think) if you wait for the proper levels, and get either the arena or TV on 27, and wait for the Tunnels on 28, pays out well. Last night lowest payout in my run was 30, highest was 45. We got a treasure vault, i suspect with the arena on 27 it will be a bit more.
Well worth it.
Average run from T3 Basil to the core will net you between 10 and 20 radiants. That is the average, you may get more (I have personally seen up to 33), you may get less. It is dependent on the floors you get and a little luck. Skepticraven was kind enough to tell you what floors are good and which are bad for radiants, although most should have been obvious just from the amount of boxes in them.
In addition there are a few missions one can do to get radiants. The Gauntlet ends at D26, which is within radiant range, just as an example.
~Gwen