Actually, I've never come across a Sobell bouzouki but a few years ago I was tempted by a second hand cittern at £3000 - probably worth a lot more now. I saw a mando for sale in 2010, also for £3000, so you'd probably have to pay a bit more than that now.
If you want to pay around the £3K for a new instrument, try N K Forster - he worked sith Stephan for many years and then set up on his own. His intruments are superb.