I think that Garner left Carlisle because there was a clause in his contract that allowed him to leave if another club bid over £1M. There was no way that Carlisle would have wanted to sell him for that amount.
Regarding transfer fees there are usually two factors - does he need to be sold or does a club desperately want to buy him? Towards the end of the Jan window there is a sort of panic that sets in with clubs at the top and bottom of the leagues (especially bottom of Prem and top of Championship). Realism doesn't come into it and at these times you can forget any sensible valuation. If a club can't get in those they wanted and they believe that safety or promotion lies in the balance then you will see some stupid bids for lower league players.
Don't mind a bit of fun but would be good just to include an explanation as to why you picked those figures rather than 2k for a goal etc. Don't expect anyone to have to go to Uni to go on this site but surely you recall pythagoras' theorem. You can't just say the hypotenuese is 'x' length, you have to explain it!!!!!!!!!