From then on more BTC were mined (at a rate of 50 for every block solved, now 25 for every block as it halves every 4 years) and the first transaction was done from Satoshi to Hal Finney at block 170 (just under 2 weeks from the first block mined).[2]
By October of 2009 the first valuation for the purchase of BTC was published (New Liberty Standard) and it used a convoluted pricing scheme to value $1 = 1,309.03 BTC.
The first actual market established was BitCoin Market[3] and they were sold for about $0.008 = 1BTC.
So since January 3rd, 2009, every 10 minutes a block was solved, giving a reward of 50 newly created BTC and in November of last year the block reward halved (so now it is 25 BTC for every block solved). It seems for over a year and a half, if you knew BitCoin existed, you could have mined a lot of them with nothing more than a CPU. Once the first GPU miners were released, that's when it became really competitive.
There is a full run down of the history of BitCoin at bitcoin.it[4]
[1] https://en.bitcoin.it/wiki/Genesis_block
[2] https://blockexplorer.com/block/00000000d1145790a8694403d406...