You can buy as many wells as you like at your current level without cheating. I've got extra 2 for only 14k coins each!!

Just visit any of your neighbours,after finishing your 5 tasks (or not) and click return home. While your home farm is loading, very quickly click on the marketplace icon as soon as it appears on the bottom right corner. Then click on the buildings tab on the top right corner.... many extra items like wells, water troughs, silos, feast tables, hen house, furnace and even extra kitchen will be available ( but it is different for each neighbour).

The prices for the items will also differ for each neighbour, but the 14k for a well and 5k for a water trough are the real bargains!

But I've had to try many times before being able to buy the extra wells and water troughs... I think it is all in the speed, as soon as the items show up, immediately click to buy, don't wait or else you will not be allowed to purchase (it says you can't buy this item now).

Just keep trying!! Some of my neighbours managed to get 15 wells!! Good luck