Actually, if my maths are correct, and I like to think they are, you're going to need a bit more than 5 sets, you'll be needing about 9 by 9 squares square (if that makes sense ). TIles are 10 by 10 cm so for about 3 by 3 ft it would have to be 81 tiles. 5 sets, assuming the stretch goal of 2 more tiles makes it would still be 21 tiles short so you'd need 7 sets to get a full board. There would be spare tiles for some variety. It looks really great but for me it's a bit to much price wise, it is worth the money but for that amount I can make 2 different tables worth of scenery which suits me better tbh.
If I had lots of cash to spare I'd go for it, as it is, it's a bit ont he steep side for me. It's worth the price considering what you get for it, in plastic, but not for me.