Wow, very helpful, thank you Robotman! Ok final question...since I have nothing left of my £100m, does that mean I can't make any transfers (or are there free ones)?
It just means the player you bring in will need to be the same or lower value than the player you transfer out.
It's also worth mentioning that player values change over time due to demand and value (nobody really knows the algorithm). so be careful of this. It's really annoying when a players value decreases from £5m to £4.9 for example as you can no longer easily swap him for a £5m player.
Player values that increase can get you too. For example if James Rodriguez (who has a base price of £7.5m) scores a hattrick against West Brom his value will likely increase to £7.6m that will be reflected when you try to buy him, but not when you sell him, when you sell you only benefit from 50% of any increased prices, but you will be punished for 100% of the decreases in value. Makes it trickier as the season goes on, but the best fantasy league managers will play the system and raise the value of their players (I'm not very good at this, it take alot of time to work it all out) then you have more funds to buy better player later in the season.
the above paragraph, might be a bit confusing...
So to go further if James Rodriguez's value went up to £7.7m then that is what he would cost that if you bought him, but if you sold him you only get 50% of the increase in value, so in this case he would be worth £7.6m if you sold him.
Actually I've just had a quick look and Calvert-Lewin has had his price increased to £7.1m, however I can only sell him for £7m. If his value goes up to £7.2m, I'd be able to sell him for £7.1m. Bare in mind these changes are slow and will be 0.1m either way every couple of weeks, most players end the season within £0.5M of their initial value either way.
What have I just typed... Lol. It's supposed to be just a bit of fun! But yeah, it gets deep. Especially when you and 5 mates put £20 in each for a £120 jackpot!