Slingshot 200AW owners - quick question

[Raider]

I'm looking to replace my small Crumpler bag with something a bit bigger and this looks just the ticket. At the moment all I need to fit in the bag is:

350D
Sigma 10-20mm
Canon 50mm F1.8
Sigma 75-300mm
+spare memory card, battery, blower etc..

But I want to be able to have the room to replace the Sigma with something bigger like the Canon 100-400L or Sigma 100-300mm F4. So will the AW200 take my normal kit and a fairly big lens?
Such a lens is around 19cm long, so pretty hefty!

Also so far I've found the bag for £55 + £5 P&P, is that the cheapest?

 

[Raider]

So a bit telephoto might be a bit of a squeeze?

 

[Raider]

Any alternatives then? I don't want a backpack because it's too inaccesible, but must shoulder bags seem too small.. grrr