On the premier league website it statesI never understood that. We don't have a limit on foreign players so not sure why the prices are that high. I would throw money at Horn right away to fix our GK issue!
http://www.premierleague.com/content/premierleague/en-gb/contact-us.html
"Each Premier League club submits a squad list, after the summer transfer windows closes. It can contain no more than 17 players who do not fulfil 'Home Grown Player' criteria. The remainder of the squad, up to a total of 25 players, must be home grown. Changes to the squad list may be made during the period of a transfer window. Under-21 players are eligible, over and above the limit of 25 players. Each player is assigned a squad number, which they wear during Premier League games. Squad lists are announced in early September."
There are also attempts to increase the number of homegrown players
http://www.bbc.com/sport/football/33892349
In 2013, Dyke created a commission with the aim of increasing the number of English players in the Premier League to 45% by 2022.
Dyke made a number of proposals to help achieve this goal, including increasing the minimum number of home-grown players in a club's first-team squad of 25 from eight to 12, phased over four years from 2016. The Premier League agreed to a consultation over the proposed changes in March 2015.