Get him to show you how to use it, eg demo it.
£50.00 sounds like a bargin, but make sure it is in good working order first, spares are easy enough to get in the UK, but expensive.
I find it a quality bit of kit, easiest a/b I've used, setup, use, & strip-down very easy, 5 years old & still using the original tube of needle lube.
The CS I have came with a 0.3 needle & head & will cope with some fine work, but I over-tightened the headset, knackered the needle & I replaced it with a 0.5 headset & needle (NOT interchangable) & this copes even better with Valejo & Tamiya acrylics.
I do mostly 1/35th Armour & 1/48th planes, but have done 1/76th, 1/87th & 1/60th armour with no problems... (other than talent not included 
)