SpookyFrank
A cheap source of teeth for aquarium gravel
A bottom of the range Brompton is 750 quid. A monthly zone 1-2 travelcard is £138.70. I think 42 quid for a month to try out the Brompton doesn't sound too bad.
But isn't the point of them that you take them on the train from Hemel Hempstead to Euston and then the tube to your job as some kind of marketing cunt? So you'd still need the travelcard. If you could do the whole trip by bike then you could just get a proper bike.