Yes, would be great to have a 17mm TS-E or even the Zeiss 21mm I keep reading about. For those
prices though it had better grow arms and legs, walk out and pose every dang tree and bush for my
landscape photo, walk back, mount itself on my camera body and reach back and hit the shutter release.
Of course that's fantasy and it's nice to hear about those sorts of lens but they are totally impractical
for lego_boy's or my budget. Currently I'm about at about his budget going towards a EF 20mm 2.8 early next
I would have to greatly disagree that his or my own budgets make getting a lens impossible. Challenging
perhaps but not impossible at all. I've been doing quite a bit of research and I'm still looking at adapting
an M42 mount, for $50US and $10 for an el cheepo adapter it's right in the price range my wallet likes.
As for other options; the 2 lenses I've also been looking are the old-ish Tamron 17-35mm f/2.8-4 and the
Canon EF 20-35mm f/3.5-4.5. Both seem like decent lens from what I have read. When they are available
the Tamron is less than $200US (about 130GB) and the Canon less than $275US (about 180GBP).
Don't be intimidated by having to adapt and old style lens. Canon's EF mount being as verstile as it is and
in our budget range it's actually a very real option.
The 17mm TSE isn't very expensive for what it does. Compared with a Master Technika and a 65mm LF lens ($12,000) and $6 per frame to shoot and $200 to scan for LF or a tech camera and MFDB (which could run $60,000+ for a decent set up) a 17mm TSE and 5D II is an incredible deal.
Granted I'm not a very good photographer and don't want to give the impression that my gear snobbishness correlates with an ability to get much out of it, but I still can't see how an UWA with T/S can be replaced with a cheap, not terribly wide zoom without any lens movements. (Unless you're shooting FF, in which case 17mm is legitimately UWA, but still lacks lens movements and sharpness.) If you're taking pictures of buildings then that's fine… if you're serious about architectural photography I just don't know how you can make this work. Maybe a panoramic head, stitching and perspective correction in post, but I couldn't pull it off. More power to you if you can.
That said, if you're not worried about having the sharpest print and are willing to recompose a bit in post, any very wide lens could work for architecture. Just stop way down to give infinite focus and fix perspective in post and it's as good as T/S.Or if you're in an area where you can back up really far from the subject, even a not-so-wide lens could work. I just wouldn't want to rely on it professionally.
Fwiw, the 14mm Samyang, while dreadfully full of distortion, is a great deal and could pull this off with a lot of post work. The 10mm f2.8 Samyang (when it's released) might be a very viable option so long as you're okay with fixing perspective in post.
I'd take the 28mm f1.8 or 30mm f1.4 but not for architecture. Of the lenses you've listed in your price range none are even close to as good for it as the kit lens (but you'll still need to fix perspective in post). For architecture, I'd get a tripod.