I'm the same as you, Macca: I scratched my head about what SMLE I wanted for about a year!
Like all of these things Brens vary in price - it depends upon what is important to you as a collector. Do you want an early British-made model with matching numbers, the 'dovetail' and all MkI parts (barrel, bipod, buttstock, carry handle, magazine release catch, charging handle were all slightly altered for the MkIM and MkII)? We sent 30,000 of those with the BEF in France and lost about 28,000 of them at Dunkirk. That means they are double in price to some other Brens.
Also some collectors love the roughed-up look as it suggests the 'weapon' was used.
One of the best places for deactivated Brens is
Saracen Exports - I've chatted with the owner and he's a nice chap with some of the lowest prices.
Mine's about in the middle: some early MkI features, wartime dated, some John Inglis parts, Enfield receiver - all good condition but the wood has been slung about a frontline somewhere and most of the bluing has gone.