That sort of money, even the lower figure, will buy just about anything second hand.
Do you really want to ride £1500, second hand, so a circa £3000 bike, every day to work? Why? Will it be secure? When it wears out will you replace the worn out bits with parts of similar quality? If you do, it will be an expensive means of going to work.
I would be spending half or a third of this amount SH and getting a very nice bike for commuting, one that's good to ride but won't cost a fortune at repair time. The saving can go towards a better bike that is used when the extra 1% of performance is required, and the fact that yuo aren't riding it every day means it will last longer.