This is the third time I've attempted a Dragon Tales - first time I ran out of time, second time I ran out of food, and this time I actually bought food. Around 75k, produced the rest with BUFFBEETS and UPGRAPES. Planting crops every 3-10 minutes is not fun. Also used my 10x food boosts on Rushrooms and Firapples, but that was only 4 hours.
The conclusion is that the food (300k or so) is the hard part by far, but if you store it up ahead of time it isn't that bad. I ran out of money yesterday, but I was able to do 5 Buffbeets+2 Upgrapes, which comes to 5*20*20 + 2*100*6= 3200 per hour. Naturally doing all upgrapes gives you more, but it's also pricier if you're doing it for hours at a time. But I did start out doing 7*100*6=4200 per hour, for the cost of 336k per hour.
Rushrooms are simpler but only 300*7=2100 per hour. But if you want it easy, that's the way to do it, if you have time. Which, now I do! Three times a day would give you around 44k per week. Adds up to about half a million, but that's the same sort of price that nightly Diamondates would run and would yield only 5600 each day vs. 6200 with triple rushrooms.