You can find a schematic and also the tubes needed here: http://www.radiomuseum.org/r/atwater_46.html
Although the tubes are listed as CX326, etc., this is roughly equivalent to the following list:
26, 26, 26, 27, 26, 112A, 112A, 80.
The 112As are sometimes listed as 12A or 212A as well.
Most of these are not so expensive if you buy good used ones. You might try advertising here in the Classified for a good used set of tubes for this radio.
If you try to buy new ones (especially globe style), things can get spendy pretty quickly on these types.