@ Peter Pan. BF didn't give me a price range for their used frames but i am thinking they were probably not too expensive considering they were second hand....? I just mailed them about that. To be fair if BRf does on request offer second hand frames for an affordable price perhaps it makes sense to just go for them. With their life time garantuee and also the fact that they have refined their product over years this might be more viable than the DIY/made to order option. Again i think they are a great company and supporting them seems nice. Oh well i'll keep you guys posted and my options open for now.

Now a cheap Twenty Inch Brompton frame that would be a very interesting option for me. Though as for the frame stiffness thing, no i have ridden neither extensivly but i took the estimations of this chart at face value. I would find it hard to believe that they are totally of the mark and the Diff. between the BF and Brompton is significant according to the chart.

http://www.pertrans.com/folding-bike-comparison.htm

As for Brompton and their design, it looks like that Merc Bike company already might have ripped them off (as some of us discussed in another thread). I have yet to receive a reply from them by mail... odd.