As title says, how much money would I aprox need for 99 farming if I plan on doing it over 2-3 months maximum?

This is highly dependent on how long you are on a day. For instance, if you were able to go around and do all of your herbs/allotments, make supercompost from the allotments and collect ranaar/snapdragon herbs, you'd be making a lot of money. You would then be able to reinvest in other seeds (fruit, tree)

I don't think I have the time to do that. How much would it cost if in theory I am making absolutely no profit?

Power-Farming is very expensive. Most people do it by mainly growing Watermelons, Palm Trees, Magic Trees, and Calquats. Use Tip.it's calculator to find how many you need from your starting level and get the prices from Zybez. There is no way to reliably get any of these seeds in any decent quantity, so you would have to buy them all yourself. Things you can do to help offset the costs are:

 

 

 

Do Manage Thy Kingdom and set 10 workers on Maples (gets ~9 nests per day)

 

 

 

Kill the Giant Mole (Get 2-5 nests per kill)

 

 

 

Woodcut with a Rabbit's Foot Necklace.

iid say any where between 13m-100m depending on how fast you want to lvl

Well, pretty much, I want to level it as fast as possible, or under 3 months atleast. 100M you think?