Before you start: This doesn't work for Building Materials or buying Buildings that are still available for coins. Works for skipping expansions requisites and everything in the store.
1 - You need Firefox or Chrome and CheatEngine
2 - Open Farmville 2 in your browser of choice
3 - See below:
For Firefox: Open CheatEngine, and go to File > Open Process. You should look in the Process List for the two Flash processes and double-click the second Flash process (underneath the first if you look top-to-bottom). Something like 0000055C-FlashPlayerPlugin_11_6_602_171.exe (may be different in your computer).
For Chrome: Open Chrome, type this in the adress bar chrome://memory-redirect/ and check for the PID of Shockwave's process. Copy it. Convert it from Decimal to Hexadecimal: [You must be registered and logged in to see this link.]
Then open CheatEngine, and look for the chrome process ending in that number. e.g.: 2908 > B5C > 00000B5C-chrome.exe
4 - Now, at the right side of your CheatEngine window, you should see Value Type: 4 Bytes. Change it to Array of Bites.
5 - Hex should now be ticked. If not, tick it.
6 - Right side of Hex, there's a text box. Copy this array there:
40 42 0F 00 40 42 0F 00 00 00 00 00
7 - Hit First Scan. It should find two or more results in the left box with two columns (Adress and Value).
8 - Select the first one and press Ctrl+A. Right-click in one of the results and click the option Add selected addresses to the addresslist. They should now be in the lower box.
9 - Hit New Scan. Search for this array the same way you did for the first one:
29 00 00 00 29 00 00 00 00 00 00 00
10 - Don't forget to hit First Scan. Multiple results should pop up in the left box.
11 - Again, select the first one, press Ctrl+A and right-click one of the results and then Add selected addresses to the addresslist.
12 - Now, in the lower box, there should be a couple of of addresses. Click the first one, press Ctrl+A and then press Alt+Enter. A new window called Type should pop up. In the Length box, change from 12 to 16.
13 - Your addresses should now have the Value made of 16 pairs of 2 numbers/letters. Open Notepad so you don't mess this next step the first time.
14 - Double-click one of the addresses that start with 40 42 0F (...) and copy the last 4 pairs of numbers to your Notepad, like this for example:
Full string: 40 42 0F 00 40 42 0F 00 00 00 00 00 F8 BE 7F 20 (different in your case)
Coins: F8 BE 7F 20
Do the same thing for the addresses that start with 29 00 00 (...) (There may be some addresses ending in 00 00 00 00. Ignore those ones, only pick one that ends with a different set of numbers.)
Full string: 29 00 00 00 29 00 00 00 00 00 00 00 58 BF 7F 20 (different in your case)
Bucks: 58 BF 7F 20
Now you should have two different arrays. F8 BE 7F 20 and 58 BF 7F 20 in my example.
15 - Search for the last array that you copied to Notepad just like you did in the previous steps (in my case I need to search for 58 BF 7F 20). Click New Scan, select the first address found, press Ctrl+A, right-click the addresses found and click the option Add selected addresses to the addresslist.
16 - Now, in the lower box, you should have your previous modified addresses and some new ones (a lot of them usually). Scroll down until you find the first small address (58 BF 7F 20 in my case) and left-click it. This should make it selected. Now, scroll till the very end of your list and Shift+Left-Click the last address in your lower box. Now, all your small addresses should be selected.
17 - Right-Click one of the selected addresses (all the others should continue selected) and choose the option Change Record > Value.
18 - A Change Value window pops up. Now, in the text box, change the value to your first array that you pasted in Notepad (mine is F8 BE 7F 20). Now all the addresses that you selected should have this value instead of the first one (58 BF 7F 20).
19 - Go to Farmville 2 and enjoy all the items and expansions you can afford for coins. Keep in mind that if you refresh your browser page, all the items in the store go back to costing Farm Bucks (all the ones that previously did).
Hope it helps.