I'd have to agree with garga it wouldn't be a bad idea to avoid some overlap but at the same time you have to remember who is buying the types and why
By that I merely wish to point out I chose my first few models for old favourites, tanks like the tiger and Sherman but soon after building and painting enough models to actually play bolt action my buying shifted to models I wanted to have so I could play more scenarios and theatres, so I went for one armoured car per side and one artillery etc and not forgetting thinking 3 or more M5 half tracks will cost a small fortune and that's just the allies!
I eventually bought 1 m5 from warlord and managed to find 2 old 1\50th scale diecast m3's for £10
After these I've chosen 1 of each 'type' I.e. pak40 and qf17 pounder , Achilles TD to match up against the tiger, sdkfz223 to match the number armoured car etc
So I would say first concentrate on producing a diversified army for the most popular countries covering all types and then once we have a nice choice , start producing the rarer desirables like rare prototypes
Although I'd love to see some of the more obscure tanks and would no doubt buy them as a business I would produce all the tanks we most use most often in the game itself
Just my thoughts
If you do decide to just produce stuff cause its cool of course I won't complain haha
VK3601 anybody?
Oooo p.s.I would REALLY love to see the marder III with the smaller gun shield (no superstructure round the gun) and more "stumpy" look modelled in our scale, (i think its the russian gun version but im not sure) you just don't see models of it and its a favourite of mine for some reason
I also have to say I Love the weight of resin tanks and could Rubicon perhaps add some sort of weighting system for us to produce that heavier feel?
I have used 'liquid gravity ', basically loads of lead balls you glue in place but its a bit of a mess, a small void in the empty areas of the model I could fill would be very useful in this respect.