Also consider whether you want a mandolin (tuned GDAE like a violin), a tenor mandolin (tuned like CGDA like a viola) or an octave mandolin (tuned GDAE but 1 octave down from a violin). All these will fit with "standard" violin fingering. There's also the bouzouki, but that's often tuned GDAD 1 octave down, and so isn't the same fingering (although you can tune that GDAE as well if you want). Each size of instrument tends to have its own character based on the body size and scale length, so although good instruments will always sound nicer than bad ones, they might not be exactly what you're after (in the same way as a good viola will never sound like a violin or a cello).

Head down to a Music Room or somewhere similar and see what you prefer.

Graham.