It all depends... but 8 x 26w cfls still uses more watts than the 4 x 42s, so go with that. 8 26w bulbs is also very cheap... at Walmart they are 97c each (2700k Lights of America). Just make sure since cfl's aren't as direct (due to its shape and no reflector) you try to focus that light. Reflective walls, and having it right by the plant helps (Mine are like an inch from my sprouts, but since they still make heat you will need a fan this close).
The only thing is... do you have 8 bulb sockets? As far as budget-ghetto goes, I would say go and pickup a simple $8 surge protector, get 3 of those lightbulb socket outlet adapters and y splitters then put them a space apart on the surge protector. Glue the back to a big turkey pan, and you have an excellent 6 light bulb socket fixture.