[wonders how much the total loans cost]
Ah! Why thanks, Nookipedia:
Animal Crossing: New Leaf
Buying House: 10,000 bells
First Expansion: 98,000 bells
Second Expansion: 198,000 bells
Second Floor: 298,000 bells
After the second story is constructed, the player may choose to expand existing rooms or construct additional rooms, in any order:
1st Second Story Expansion: 498,000 bells (upgraded to 6 by 6 squares)
2nd Second Story Expansion: 598,000 bells (upgraded to 8 by 8 squares)
Basement: 428,000 bells (4 by 4 squares)
1st Basement Expansion: 498,000 bells (upgraded to 6 by 6 squares)
2nd Basement Expansion: 598,000 bells (upgraded to 8 by 8 squares)
Ground Floor Left Room: 348,000 bells (4 by 4 squares)
1st Ground Floor Left Room Expansion: 498,000 bells (upgraded to 6 by 6 squares)
2nd Ground Floor Left Room Expansion: 598,000 bells (upgraded to 8 by 8 squares)
Ground Floor Right Room: 348,000 bells (4 by 4 squares)
1st Ground Floor Right Room Expansion: 498,000 bells (upgraded to 6 by 6 squares)
2nd Ground Floor Right Room Expansion: 598,000 bells (upgraded to 8 by 8 squares)
Ground Floor Back Room: 348,000 bells (4 by 4 squares)
1st Ground Floor Back Room Expansion: 498,000 bells (upgraded to 6 by 6 squares)
2nd Ground Floor Back Room Expansion: 598,000 bells (upgraded to 8 by 8 squares)
Total Cost: 7,595,800 Bells
I'm not sure how much you plan to expand everything, but I've currently got 2.3mil in in-game Bells. I won't be able to trade until around 9:15pm Central time tonight, unfortunately, but if you don't have any other offers, let me know, yeah?