In my experience you can pay a lot for something that is of mediocre quality. That goes for sofas in general but we had a look at Sofology a year or two back and they seemed to bear that out.
We have had most joy with Darlings of Chelsea, particularly their ex-display/ returns, which are online. Really like Fama sofas, which darlings do. They seem to fit our decor. One thing to watch out for is that they do not generally advertise the manufacturers name. You will look through and see tetrad as well as the Italian leather stuff without it being advertised as such.
If you like Tetrad styling then they have an outlet in Preston – stock is advertised on their facebook page I think.