Very close to the Solution of "L Figo 007" & "OlsAbsss x" but I have some inprovements. It is also mainly more for people with already a lot of players but mostly Non-Rare.
Again values are about (thnx Figo, it helped me a lot):
BRONZE - 55.000
BRONZE RARE - 130.000
SILVER - 80.000
SILVER RARE - 185.000
GOLD - 140.000
GOLD RARE - 265.000
"Figo" & "Mr McCullxch" states Gold players for 300, but better is to buy 2 Bronze Rare for 150 each, as this is more worth for your Team Total (140.000 vs. 260.000). If you start running out on Bronze Rare, start buying Sliver Rare for 250, 300 max.
Using the Web App: http://www.ea.com/uk/football/fifa-ultimate-team
, works very good, as you can open a second tab with the playerlist you already have, to look up if you don't buy a double.
Selling all Balls, Stadiums & Club Logo/Jersey's you don't need gives coins you can use for players when you sell them.
My main way to reach it in a short time (35M. in 1 week) is if you have already a big group of players, is to sell all Non-Rare Players you have slowly. The Bronze & Silver I selled for 150-200 (start-buyout) and buyed a Bronze Rare for back (rise of 50.000+, depending on Bronze or Silver sold, per player), the Non-Rare Gold I selled for 450-600 (sometimes higher and mostly buyed trough buyout) and could then buy 4 Bronze Rare for back (rise of 380.000 per player).
Look for Tournaments when you sell, now their is one where you need 18 from Primier or BBVA, so those players get buyed faster en for a small higher amount.
If you not really want to play anymore you can sell your Club-Staff also. When I was on 50 Million a week ago and started to do what I described above. I not had played any matches anymore and had maybe only 2000 coins. I had already the 653 players stated by "OlsAbsss x" but mine where mostly Non-Rare.