Hi mujana, thanks...
I think the Hex 57mm f1.2 cost me just over £200 - that was the most expensive (and worth every penny) - you should be able to find a good 57mm f1.4 for less than £50... if you look at previous (completed) auctions you should see the going rate for these.
Remember also, that you'll need to do a conversion - this took me a fair bit of practice, and in the end I've moved to the method devised by my friend Pete Snaar... details on his website here :
Scroll to bottom half of this page
Hope that helps! if you'd been in the UK, I would have offered to show you exactly how to do the conversion at one of our UK Photo Safari events - I'd probably even have a spare lens or two for sale.
Kind Regards
Brian