Hi Alun,
The ALPY600 is an impressive tool for measuring active galaxy redshifts. For example Etienne Bertrand has found it is possible to get down to mag 15-16 on active galaxy and QSO with a C8 scope. You might be interested in his growing collection that he has been reporting on the ARAS forum here.
http://www.spectro-aras.com/forum/viewforum.php?f=6
His latest ( QSO 1247+267 at z=2 and V mag 16) is here
http://www.spectro-aras.com/forum/viewtopic.php?f=6&t=1663&p=7726
Cheers
Robin