I agree with SanDiego1K, ebags.com, their own range, is the way to go.... you'll need to arrange delivery in the US and collect on a trip over there. There is a more limited range at ebags.co.uk, but the prices are £=$ for their own stuff.

Have a search for the "mother lode" in the mini size, only on the US site. A fantastic, versatile, carry on.

I think they also stock Briggs and Riley in the UK, but my ebags purchases have been great. They also have review on site, so you can size up other bags/makes before you purchase.