As I've written before, I'm playing "Plant Tycoon" regularly - right while I'm writing this, actually. It's the ideal game to run while doing something else, because it usually takes about 50 minutes to raise a plant.
I've already gotten the best soil, the best water and the best pruning shears. I've also bought all the stuff for my nursery, except for the fountain. I'm currently saving for it, but it will take some time (it costs 4,500$ and I'm making an average of about 40$ per plant). I also spent 2,000$ on an extinct seed lately, but I'll get that back from the plants I can now create with it. I've gotten a little over 50 known plants now (and had to go down to keeping one seed per plant, instead of two - problems with the space, even though I've gotten all three seed boxes by now).
When I want to make money quickly I choose and pollinate expensive plants and then sell 15 of those (15 is the maximum of plants I can grow at the same time) that brings up the money quickly - as the most expensive plants I've got at the moment sells for well over 80$ each. Do this a couple of times and even the nice fountain is inside reach...
Well, we shall see, because an interesting seed is worth more to me than the fountain. I've got loads of visitors every time I open the nursery anyway.