Clive,
The SBiG spectroscopes are no longer manufactured and were designed for use solely with SBiG cameras.
The Baader Dados has a 200 and 900 l/mm grating option so is more versatile than the fixed 300 l/mm in the LISA.
(Check out Richard Walker's spectral Atlas - he uses the Dados
http://www.ursusmajor.ch/astrospektr...age/index.html
- down the bottom rhs for the latest English version)
On our Astronomical_spectroscopy group we have the plans available for a simple DIY "faint-object" spectroscope - the MG80.
This uses an adjustable 300 l/mm grating, an 80mm collimator and recommends a 50mm f1.8 camera lens for imaging the spectrum.
There's also a FC125, a folded Classical design with various options for the grating (150/300/600 etc), designed around a 125mm f5 collimator...
Let me know if I can help.