We've all been there mate. Think of it as a rite of passage, or whatever doesn't kill you makes you stronger, or live and learn, or really whatever I can say that will make you not give up the quest so <INSERT INSPIRATIONAL QUOTE OF ENCOURAGEMENT HERE>.
I had basically discounted all the Sennheisers because of the veil. I really liked the clarity of the Superlux, and even the Flats sounded clearer than the PX100-II. Then I looked up the various brands 'signature' sounds and the veil was one of Sennheisers. If the HD238s are only slightly veiled at the top then I might not even notice, not really being an audiophile.
I think that the PX 100-II are uniquely different from almost everything else in and around it's range, including other Sennheisers, so I wouldn't be so quick to discount all of them. The thing that makes this particular rec hard for me is the requirement that it must be supraaural and open/semi-open within that price range. If you take that away, I'd be inclined to advise that you take a look at the Sennheiser HD 215. I assure you, that will redefine what you think of Sennheiser. If you're interested in learning more about it, I have a rather lengthy review on it here. The price on it tends to fluctuate a bit, and I have seen it come down to within your price range.
The AKG K420s are £39 on Amazon, so slightly easier on the bank balance.. The Grados cost £85, so really out of my price range. I had been considering the MEElectronics HT-21s, as they were cheap and decently reviewed for clarity. I seem to recall Beyerdynamic as being one to look at further as well, based on the brand 'signature', though it was about 3am and I was falling asleep so I could be wrong there...
Gotcha. I haven't heard the Meelec HT-21 so I can't say. But as for Beyers, my favorite (as well as preferred choice for you) would be WAAYYYY outside your budget.