I would buy from ...

Ducati London South in Croydon
Pro V Twins in Godstone
Snells in Alton
MotoRapido in Winchester
P&H in Crawley (thats where I bought my bike)

I wouldn't buy from

OnYerBike in Aylesbury
Pegasus in Reading

My suggestions above are based on my own experiences and those of my friends, they do not guarantee anything but are an answer to your question.

A clean 748R can cost anything up to £7.5k for a mint one, you find your bike and pays tour money.

There are a couple for sale in the market place here.

the 748R is an acquired taste and people that want them, really want them and thos that don't can't always understand the devotion to them when for similar money the new 749 is available with warranty ...

Happy shopping and welcome ...